Index

MDN JavaScript pages

This page lists all MDN JavaScript pages along with their summary and tags.

Found 926 pages:

# Page Tags and summary
1 JavaScript JavaScript, Landing, Learn, l10n:priority
JavaScript (JS) is a lightweight, interpreted, or just-in-time compiled programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB and Adobe Acrobat.
2 A re-introduction to JavaScript (JS tutorial) CodingScripting, Guide, Intermediate, Intro, JavaScript, Learn
Why a re-introduction? Because JavaScript is notorious for being the world's most misunderstood programming language. It is often derided as being a toy, but beneath its layer of deceptive simplicity, powerful language features await. JavaScript is now used by an incredible number of high-profile applications, showing that deeper knowledge of this technology is an important skill for any web or mobile developer.
3 About JavaScript Beginner, Introduction, JavaScript
JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, and is best known as the scripting language for Web pages, but it's used in many non-browser environments as well. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.
4 Closures Closure, ES5, Intermediate, JavaScript, Reference
A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function. In JavaScript, closures are created every time a function is created, at function creation time.
5 Concurrency model and the event loop Advanced, Event Loop, Event Management, Event Queue, Handling Events, JavaScript, events
JavaScript has a concurrency model based on an event loop, which is responsible for executing the code, collecting and processing events, and executing queued sub-tasks.
6 Differential inheritance in JavaScript CodingScripting, Example, Inheritance, JavaScript
Differential Inheritance is a common inheritance model used by prototype-based programming languages such as JavaScript. It operates on the principle that most objects are derived from other, more general objects, and only differ in a few small aspects; while usually maintaining a list of pointers internally to other objects which the object differs from.
7 Enumerability and ownership of properties JavaScript
Enumerable properties are those properties whose internal enumerable flag is set to true, which is the default for properties created via simple assignment or via a property initializer (properties defined via Object.defineProperty and such default enumerable to false). Enumerable properties show up in for...in loops unless the property's key is a Symbol. Ownership of properties is determined by whether the property belongs to the object directly and not to its prototype chain. Properties of an object can also be retrieved in total. There are a number of built-in means of detecting, iterating/enumerating, and retrieving object properties, with the chart showing below which are available. Some sample code follows which demonstrates how to obtain the missing categories.
8 Equality comparisons and sameness Comparison, Equality, Intermediate, JS, JavaScript, NaN, SameValue, SameValueZero, Sameness
There are four equality algorithms in ES2015:
9 Index Index, JavaScript, MDN Meta
This page lists all MDN JavaScript pages along with their summary and tags.
10 Inheritance and the prototype chain Advanced, Guide, Inheritance, JavaScript, OOP
JavaScript is a bit confusing for developers experienced in class-based languages (like Java or C++), as it is dynamic and does not provide a class implementation per se (the class keyword is introduced in ES2015, but is syntactical sugar, JavaScript remains prototype-based).
11 Introduction to using XPath in JavaScript Add-ons, DOM, Extensions, JavaScript, Transforming_XML_with_XSLT, Web Development, XML, XPath, XSLT
This document describes the interface for using XPath in JavaScript internally, in extensions, and from websites. Mozilla implements a fair amount of the DOM 3 XPath, which means that XPath expressions can be run against both HTML and XML documents.
12 JavaScript Guide Guide, JavaScript, l10n:priority
The JavaScript Guide shows you how to use JavaScript and gives an overview of the language. If you need exhaustive information about a language feature, have a look at the JavaScript reference.
13 Control flow and error handling Beginner, Guide, JavaScript, l10n:priority
JavaScript supports a compact set of statements, specifically control flow statements, that you can use to incorporate a great deal of interactivity in your application. This chapter provides an overview of these statements.
14 Details of the object model Guide, Intermediate, JavaScript, Object, l10n:priority
JavaScript is an object-based language based on prototypes, rather than being class-based. Because of this different basis, it can be less apparent how JavaScript allows you to create hierarchies of objects and to have inheritance of properties and their values. This chapter attempts to clarify the situation.
15 Expressions and operators Beginner, Expressions, Guide, JavaScript, Operators, l10n:priority
This chapter describes JavaScript's expressions and operators, including assignment, comparison, arithmetic, bitwise, logical, string, ternary and more.
16 Functions Beginner, Functions, Guide, JavaScript, l10n:priority
Functions are one of the fundamental building blocks in JavaScript. A function is a JavaScript procedure—a set of statements that performs a task or calculates a value. To use a function, you must define it somewhere in the scope from which you wish to call it.
17 Grammar and types Guide, JavaScript, l10n:priority
This chapter discusses JavaScript's basic grammar, variable declarations, data types and literals.
18 Indexed collections Guide, JavaScript, Method, l10n:priority
This chapter introduces collections of data which are ordered by an index value. This includes arrays and array-like constructs such as Array objects and TypedArray objects.
19 Introduction Beginner, Guide, Introduction, JavaScript, l10n:priority
This chapter introduces JavaScript and discusses some of its fundamental concepts.
20 Iterators and generators Guide, Intermediate, JavaScript, l10n:priority
Processing each of the items in a collection is a very common operation. JavaScript provides a number of ways of iterating over a collection, from simple for loops to map() and filter(). Iterators and Generators bring the concept of iteration directly into the core language and provide a mechanism for customizing the behavior of for...of loops.
21 JavaScript modules Guide, JavaScript, Modules, export, import
This guide gives you all you need to get started with JavaScript module syntax.
22 Keyed collections Collections, Guide, JavaScript, Map, l10n:priority, set
This chapter introduces collections of data which are ordered by a key; Map and Set objects contain elements which are iterable in the order of insertion.
23 Loops and iteration Guide, JavaScript, Loop, Syntax, l10n:priority
Loops offer a quick and easy way to do something repeatedly. This chapter of the JavaScript Guide introduces the different iteration statements available to JavaScript.
24 Meta programming Guide, JavaScript, Proxy, Reflect, l10n:priority
Starting with ECMAScript 2015, JavaScript gains support for the Proxy and Reflect objects allowing you to intercept and define custom behavior for fundamental language operations (e.g. property lookup, assignment, enumeration, function invocation, etc). With the help of these two objects you are able to program at the meta level of JavaScript.
25 Numbers and dates Calculation, Dates, FP, Floating Point, Floating-Point, Guide, Integer, JavaScript, Math, Numbers, Numeric, l10n:priority
This chapter introduces the concepts, objects and functions used to work with and perform calculations using numbers and dates in JavaScript.
26 Regular expressions Guide, Intermediate, JavaScript, Reference, RegExp, Regular Expressions, regex
Regular expressions are patterns used to match character combinations in strings. In JavaScript, regular expressions are also objects. These patterns are used with the exec() and test() methods of RegExp, and with the match(), matchAll(), replace(), search(), and split() methods of String. This chapter describes JavaScript regular expressions.
27 Assertions Assertions, JavaScript, Reference, Regular Expressions, regex
Assertions indicate in some way that a match is possible. Assertions include look-ahead, look-behind, and conditional expressions.
28 Boundaries Boundaries, JavaScript, Reference, Regular Expressions, regex
Boundaries Indicate the beginnings and endings of lines and words.
29 Character classes JavaScript, Reference, RegExp, Regular Expressions, character classes
Character classes distinguish kinds of characters such as, for example, distinguishing between letters and digits.
30 Groups and ranges JavaScript, Reference, Regular Expressions, groups, ranges, regex
Groups and ranges indicate groups and ranges of expression characters.
31 Quantifiers JavaScript, Reference, Regular Expressions, quantifiers, regex
Quantifiers indicate numbers of characters or expressions to match.
32 Unicode property escapes JavaScript, Reference, Regular Expressions, regex, unicode property escapes
Unicode property escapes in Regular Expressions allows for matching unicode characters based on unicode character properties. It allows for distinguishing between types of characters such as upper and lower case letters, math symbols, and punctuation. A feature learnt from PCRE et al, it is available for the RegExp object since ES2018.
33 Text formatting Guide, JavaScript, l10n:priority
This chapter introduces how to work with strings and text in JavaScript.
34 Using Promises Guide, Intermediate, JavaScript, Promise, Promises, asynchronous, l10n:priority
A Promise is an object representing the eventual completion or failure of an asynchronous operation. Since most people are consumers of already-created promises, this guide will explain consumption of returned promises before explaining how to create them.
35 Working with objects Beginner, Comparing object, Constructor, Document, Guide, JavaScript, Object, l10n:priority
JavaScript is designed on a simple object-based paradigm. An object is a collection of properties, and a property is an association between a name (or key) and a value. A property's value can be a function, in which case the property is known as a method. In addition to objects that are predefined in the browser, you can define your own objects. This chapter describes how to use objects, properties, functions, and methods, and how to create your own objects.
36 JavaScript data types and data structures Beginner, JavaScript, Types
Programming languages all have built-in data structures, but these often differ from one language to another. This article attempts to list the built-in data structures available in JavaScript and what properties they have; these can be used to build other data structures. Wherever possible, comparisons with other languages are drawn.
37 JavaScript language resources Advanced, ECMA, JavaScript
ECMAScript is the scripting language that forms the basis of JavaScript. ECMAScript standardized by the ECMA International standards organization in the ECMA-262 and ECMA-402 specifications. The following ECMAScript standards have been approved or are being worked on:
38 JavaScript reference Code, ECMAScript, ECMAScript6, ES6, JS, JavaScript, Reference, es, l10n:priority, programming
This part of the JavaScript section on MDN serves as a repository of facts about the JavaScript language. Read more about this reference.
39 About the JavaScript reference JavaScript
The JavaScript reference serves as a repository of facts about the JavaScript language. The entire language is described here in detail. As you write JavaScript code, you'll refer to these pages often (thus the title "JavaScript reference"). If you're learning JavaScript, or need help understanding some of its capabilities or features, check out the JavaScript guide.
40 Classes Classes, Constructors, ECMAScript 2015, Inheritance, Intermediate, JavaScript
JavaScript classes, introduced in ECMAScript 2015, are primarily syntactical sugar over JavaScript's existing prototype-based inheritance. The class syntax does not introduce a new object-oriented inheritance model to JavaScript.
41 Class fields Classes, JavaScript
Both static and instance public fields are writable, enumerable, configurable properties. As such, unlike their private counterparts, they participate in prototype inheritance.
42 constructor Classes, ECMAScript 2015, JavaScript
The constructor method is a special method for creating and initializing an object created within a class.
43 extends Classes, ECMAScript 2015, JavaScript
The extends keyword is used in class declarations or class expressions to create a class which is a child of another class.
44 static Classes, ECMAScript 2015, JavaScript, Static
The static keyword defines a static method for a class. Static methods aren't called on instances of the class. Instead, they're called on the class itself.
45 Deprecated and obsolete features Deprecated, JavaScript, Obsolete
This page lists features of JavaScript that are deprecated (that is, still available but planned for removal) and obsolete (that is, no longer usable).
46 The legacy Iterator protocol ES2015, JavaScript, Legacy Iterator
Firefox, prior to version 26 implemented another iterator protocol that is similar to the standard ES2015 Iterator protocol.
47 Expressions and operators JavaScript, Operators, Overview, Reference
This chapter documents all the JavaScript language operators, expressions and keywords.
48 Arithmetic operators JavaScript, Operator
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value. The standard arithmetic operators are addition (+), subtraction (-), multiplication (*), and division (/).
49 Array comprehensions JavaScript, Non-standard, Obsolete, Operator, Reference
The array comprehension syntax was a JavaScript expression which allowed you to quickly assemble a new array based on an existing one. However, it has been removed from the standard and the Firefox implementation. Do not use it!
50 Assignment operators JavaScript, Operator
An assignment operator assigns a value to its left operand based on the value of its right operand.
51 Bitwise operators JavaScript, Operator, Reference
Bitwise operators treat their operands as a sequence of 32 bits (zeroes and ones), rather than as decimal, hexadecimal, or octal numbers. For example, the decimal number nine has a binary representation of 1001. Bitwise operators perform their operations on such binary representations, but they return standard JavaScript numerical values.
52 Comma operator JavaScript, Operator, Reference
The comma operator evaluates each of its operands (from left to right) and returns the value of the last operand.
53 Comparison operators JavaScript, Operator, Reference
JavaScript has both strict and type–converting comparisons. A strict comparison (e.g., ===) is only true if the operands are of the same type and the contents match. The more commonly-used abstract comparison (e.g. ==) converts the operands to the same type before making the comparison. For relational abstract comparisons (e.g., <=), the operands are first converted to primitives, then to the same type, before comparison.
54 Conditional (ternary) operator Conditional, Decision, JS, JavaScript, Operator, Reference, else, if, ternary
The conditional (ternary) operator is the only JavaScript operator that takes three operands: a condition followed by a question mark (?), then an expression to execute if the condition is truthy followed by a colon (:), and finally the expression to execute if the condition is falsy.
55 Destructuring assignment Destructuring, Destructuring_assignment, ECMAScript 2015, ES6, JavaScript, Nested object and array destructuring, Operator
The destructuring assignment syntax is a JavaScript expression that makes it possible to unpack values from arrays, or properties from objects, into distinct variables.
56 Expression closures Function, JavaScript, Non-standard, Obsolete, Operator, Reference
Expression closures are a shorthand function syntax for writing simple functions.
57 Function expression Function, JavaScript, Operator, Primary Expressions
The function keyword can be used to define a function inside an expression.
58 Generator comprehensions Iterator, JavaScript, Non-standard, Obsolete, Reference
The generator comprehension syntax was a JavaScript expression which allowed you to quickly assemble a new generator function based on an existing iterable object. However, it has been removed from the standard and the Firefox implementation. Do not use it!
59 Grouping operator JavaScript, Operator, Primary Expressions
The grouping operator ( ) controls the precedence of evaluation in expressions.
60 Legacy generator function expression JavaScript, Legacy Iterator, Non-standard, Obsolete, Operator, Reference
The function keyword can be used to define a legacy generator function inside an expression. To make the function a legacy generator, the function body should contain at least one yield expression.
61 Logical operators JavaScript, Logic, Logical Operators, Not, Operator, Reference, and, or
Logical operators are typically used with Boolean (logical) values. When they are, they return a Boolean value. However, the && and || operators actually return the value of one of the specified operands, so if these operators are used with non-Boolean values, they will return a non-Boolean value.
62 Nullish coalescing operator JavaScript, Operator, Reference, nullish coalescing
The nullish coalescing operator (??) is a logical operator that returns its right-hand side operand when its left-hand side operand is null or undefined, and otherwise returns its left-hand side operand.
63 Object initializer ECMAScript 2015, JSON, JavaScript, Literal, Methods, Object, Primary Expression, computed, mutation, properties
Objects can be initialized using new Object(), Object.create(), or using the literal notation (initializer notation). An object initializer is a comma-delimited list of zero or more pairs of property names and associated values of an object, enclosed in curly braces ({}).
64 Operator precedence JavaScript, Operator, precedence
Operator precedence determines the way in which operators are parsed with respect to each other. Operators with higher precedence become the operands of operators with lower precedence.
65 Optional chaining Chaining, Experimental, JavaScript, Operator, Optional chaining, Reference
The ?. operator functions similarly to the . chaining operator, except that instead of causing an error if a reference is nullish (null or undefined), the expression short-circuits with a return value of undefined.
66 Pipeline operator Chaining, Experimental, JavaScript, Operator, Pipeline
The experimental pipeline operator |> (currently at stage 1) pipes the value of an expression into a function. This allows the creation of chained function calls in a readable manner. The result is syntactic sugar in which a function call with a single argument can be written like this:
67 Property accessors JavaScript, Operator, Reference
Property accessors provide access to an object's properties by using the dot notation or the bracket notation.
68 Spread syntax ECMAScript 2015, Iterator, JavaScript, Reference
Spread syntax allows an iterable such as an array expression or string to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected, or an object expression to be expanded in places where zero or more key-value pairs (for object literals) are expected.
69 async function expression Function, JavaScript, Operator, Primary Expression
The async function keyword can be used to define async functions inside expressions.
70 await Function, JavaScript, Operator, Primary Expression
The await operator is used to wait for a Promise. It can only be used inside an async function.
71 class expression Classes, ECMAScript 2015, Expression, JavaScript, Operator, Reference
The class expression is one way to define a class in ECMAScript 2015. Similar to function expressions, class expressions can be named or unnamed. If named, the name of the class is local to the class body only. JavaScript classes use prototype-based inheritance.
72 delete operator JavaScript, Memory Management, Object, Operator, Property, Reference, Release, Unary, delete
The JavaScript delete operator removes a property from an object; if no more references to the same property are held, it is eventually released automatically.
73 function* expression ECMAScript 2015, Function, Iterator, JavaScript, Operator, Primary Expression
The function* keyword can be used to define a generator function inside an expression.
74 in operator JavaScript, Operator, Relational Operators
The in operator returns true if the specified property is in the specified object or its prototype chain.
75 instanceof JavaScript, Object, Operator, Prototype, Relational Operators, instanceof
The instanceof operator tests whether the prototype property of a constructor appears anywhere in the prototype chain of an object.
76 new operator JavaScript, Left-hand-side expressions, Operator, Reference
The new operator lets developers create an instance of a user-defined object type or of one of the built-in object types that has a constructor function.
77 new.target Classes, ECMAScript 2015, JavaScript, Reference
The new.target pseudo-property lets you detect whether a function or constructor was called using the new operator. In constructors and functions invoked using the new operator, new.target returns a reference to the constructor or function. In normal function calls, new.target is undefined.
78 super Classes, ECMAScript 2015, JavaScript, Left-hand-side expressions, Operator
The super keyword is used to access and call functions on an object's parent.
79 this JavaScript, Operator, Primary Expressions, Reference, this
A function's this keyword behaves a little differently in JavaScript compared to other languages. It also has some differences between strict mode and non-strict mode.
80 typeof JavaScript, Operator, Reference, Unary
The typeof operator returns a string indicating the type of the unevaluated operand.
81 void operator JavaScript, Operator, Reference, Unary
The void operator evaluates the given expression and then returns undefined.
82 yield ECMAScript 2015, Generators, Iterator, JavaScript, Operator
The yield keyword is used to pause and resume a generator function (function* or legacy generator function).
83 yield* ECMAScript 2015, Generators, Iterable, Iterator, JavaScript, Operator, Reference
The yield* expression is used to delegate to another generator or iterable object.
84 Functions Constructor, Function, Functions, JavaScript, Parameter, parameters
Generally speaking, a function is a "subprogram" that can be called by code external (or internal in the case of recursion) to the function. Like the program itself, a function is composed of a sequence of statements called the function body. Values can be passed to a function, and the function will return a value.
85 Arrow function expressions ECMAScript 2015, Functions, Intermediate, JavaScript, Reference
An arrow function expression is a syntactically compact alternative to a regular function expression, although without its own bindings to the this, arguments, super, or new.target keywords. Arrow function expressions are ill suited as methods, and they cannot be used as constructors.
86 Default parameters ECMAScript 2015, Functions, JavaScript
Default function parameters allow named parameters to be initialized with default values if no value or undefined is passed.
87 Method definitions ECMAScript 2015, Functions, JavaScript, Object, Syntax
Starting with ECMAScript 2015, a shorter syntax for method definitions on objects initializers is introduced. It is a shorthand for a function assigned to the method's name.
88 Rest parameters Functions, JavaScript, Rest, Rest parameters
The rest parameter syntax allows us to represent an indefinite number of arguments as an array.
89 The arguments object Functions, JavaScript, Reference, arguments
arguments is an Array-like object accessible inside functions that contains the values of the arguments passed to that function.
90 arguments.callee Deprecated, Functions, JavaScript, Property, arguments
The arguments.callee property contains the currently executing function.
91 arguments.caller Functions, JavaScript, Obsolete, Property, arguments
The obsolete arguments.caller property used to provide the function that invoked the currently executing function. This property has been removed and no longer works.
92 arguments.length Functions, JavaScript, Property, arguments
The arguments.length property contains the number of arguments passed to the function.
93 arguments[@@iterator]() Deprecated, Functions, JavaScript, Property, arguments
The initial value of the @@iterator property is the same function object as the initial value of the Array.prototype.values property.
94 getter ECMAScript 2015, ECMAScript 5, Functions, JavaScript
The get syntax binds an object property to a function that will be called when that property is looked up.
95 setter ECMAScript 5, Functions, JavaScript
The set syntax binds an object property to a function to be called when there is an attempt to set that property.
96 Iteration protocols ECMAScript 2015, Intermediate, Iterable, Iterator, JavaScript
A couple of additions to ECMAScript 2015 aren't new built-ins or syntax, but protocols. These protocols can be implemented by any object respecting some conventions.
97 JavaScript error reference Debugging, Error, Errors, Exception, JavaScript, exceptions
Below, you'll find a list of errors which are thrown by JavaScript. These errors can be a helpful debugging aid, but the reported problem isn't always immediately clear. The pages below will provide additional details about these errors. Each error is an object based upon the Error object, and has a name and a message.
98 Error: Permission denied to access property "x" Error, Errors, JavaScript, Security
There was attempt to access an object for which you have no permission. This is likely an <iframe> element loaded from a different domain for which you violated the same-origin policy.
99 InternalError: too much recursion Errors, InternalError, JavaScript
When there are too many function calls, or a function is missing a base case, JavaScript will throw this error.
100 RangeError: argument is not a valid code point Errors, JavaScript, RangeError
String.fromCodePoint() throws this error when passed NaN values, negative Integers (-1), non-Integers (5.4), or values larger than 0x10FFFF (1114111).
101 RangeError: invalid array length Errors, JavaScript, RangeError
RangeError
102 RangeError: invalid date Errors, JavaScript, RangeError
RangeError
103 RangeError: precision is out of range Errors, JavaScript, RangeError
RangeError
104 RangeError: radix must be an integer Errors, JavaScript, RangeError
RangeError
105 RangeError: repeat count must be less than infinity Errors, JavaScript, RangeError
RangeError
106 RangeError: repeat count must be non-negative Errors, JavaScript, RangeError
RangeError
107 ReferenceError: "x" is not defined Error, JavaScript, ReferenceError
ReferenceError.
108 ReferenceError: assignment to undeclared variable "x" Errors, JavaScript, ReferenceError, Strict Mode
ReferenceError warning in strict mode only.
109 ReferenceError: can't access lexical declaration`X' before initialization Errors, JavaScript, ReferenceError
ReferenceError
110 ReferenceError: deprecated caller or arguments usage Errors, JavaScript, Strict Mode, Warning
A strict-mode-only warning that a ReferenceError occurred. JavaScript execution won't be halted.
111 ReferenceError: invalid assignment left-hand side Errors, JavaScript, ReferenceError
ReferenceError.
112 ReferenceError: reference to undefined property "x" Errors, JavaScript, ReferenceError, Strict Mode
(Firefox only) ReferenceError warning which is reported only if javascript.options.strict preference is set to true.
113 SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated Error, JavaScript, Strict Mode, SyntaxError
SyntaxError in strict mode only.
114 SyntaxError: "use strict" not allowed in function with non-simple parameters Errors, JavaScript, TypeError
SyntaxError.
115 SyntaxError: "x" is a reserved identifier Error, Errors, JavaScript, SyntaxError
SyntaxError
116 SyntaxError: JSON.parse: bad parsing Errors, JSON, JavaScript, Method, Property, SyntaxError
SyntaxError
117 SyntaxError: Malformed formal parameter Errors, JavaScript, SyntaxError
SyntaxError
118 SyntaxError: Unexpected token Errors, JavaScript, SyntaxError
SyntaxError
119 SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead Errors, JavaScript, Source maps
A warning that a SyntaxError occurred. JavaScript execution won't be halted.
120 SyntaxError: a declaration in the head of a for-of loop can't have an initializer Error, JavaScript, SyntaxError
SyntaxError
121 SyntaxError: applying the 'delete' operator to an unqualified name is deprecated Error, Errors, JavaScript, SyntaxError
SyntaxError in strict mode only.
122 SyntaxError: for-in loop head declarations may not have initializers Error, JavaScript, Strict Mode, SyntaxError
SyntaxError in strict mode only.
123 SyntaxError: function statement requires a name Error, Errors, JavaScript, SyntaxError
SyntaxError
124 SyntaxError: identifier starts immediately after numeric literal Error, Errors, JavaScript, SyntaxError
SyntaxError
125 SyntaxError: illegal character Error, Errors, JavaScript, SyntaxError
SyntaxError
126 SyntaxError: invalid regular expression flag "x" Error, JavaScript, SyntaxError
SyntaxError
127 SyntaxError: missing ) after argument list Errors, JavaScript, SyntaxError
SyntaxError.
128 SyntaxError: missing ) after condition Error, Errors, JavaScript, SyntaxError
SyntaxError
129 SyntaxError: missing : after property id Error, Errors, JavaScript, SyntaxError
SyntaxError
130 SyntaxError: missing ; before statement Errors, JavaScript, SyntaxError
SyntaxError.
131 SyntaxError: missing = in const declaration Error, JavaScript, SyntaxError
SyntaxError
132 SyntaxError: missing ] after element list Errors, JavaScript, SyntaxError
SyntaxError.
133 SyntaxError: missing formal parameter Error, Errors, JavaScript, SyntaxError
SyntaxError
134 SyntaxError: missing name after . operator Error, Errors, JavaScript, SyntaxError
SyntaxError
135 SyntaxError: missing variable name Error, Errors, JavaScript, SyntaxError
SyntaxError
136 SyntaxError: missing } after function body Error, Errors, JavaScript, SyntaxError
SyntaxError
137 SyntaxError: missing } after property list Errors, JavaScript, SyntaxError
SyntaxError
138 SyntaxError: redeclaration of formal parameter "x" Errors, JavaScript, SyntaxError
SyntaxError
139 SyntaxError: return not in function Errors, JavaScript, SyntaxError
SyntaxError.
140 SyntaxError: test for equality (==) mistyped as assignment (=)? Errors, JavaScript, SyntaxError
(Firefox only) SyntaxError warning which is reported only if javascript.options.strict preference is set to true.
141 SyntaxError: unterminated string literal Errors, JavaScript, SyntaxError
SyntaxError
142 TypeError: "x" has no properties Errors, JavaScript, TypeError
TypeError.
143 TypeError: "x" is (not) "y" Errors, JavaScript, TypeError
TypeError.
144 TypeError: "x" is not a constructor Errors, JavaScript, TypeError
TypeError
145 TypeError: "x" is not a function Errors, JavaScript, TypeError
TypeError.
146 TypeError: "x" is not a non-null object Error, Errors, JavaScript, TypeError
TypeError
147 TypeError: "x" is read-only Errors, JavaScript, TypeError
TypeError
148 TypeError: 'x' is not iterable Error, JavaScript, Reference, TypeError
TypeError
149 TypeError: More arguments needed Errors, JavaScript, TypeError
TypeError.
150 TypeError: Reduce of empty array with no initial value Error, JavaScript, Reference, TypeError
TypeError
151 TypeError: X.prototype.y called on incompatible type Errors, JavaScript, TypeError
TypeError
152 TypeError: can't access dead object Addons, Error, Errors, JavaScript
TypeError
153 TypeError: can't access property "x" of "y" Errors, JavaScript, TypeError
TypeError.
154 TypeError: can't assign to property "x" on "y": not an object Error, Errors, JavaScript, TypeError
TypeError.
155 TypeError: can't define property "x": "obj" is not extensible Error, Errors, JavaScript, TypeError
TypeError
156 TypeError: can't delete non-configurable array element Error, Errors, JavaScript, TypeError
TypeError
157 TypeError: can't redefine non-configurable property "x" Error, Errors, JavaScript, TypeError
TypeError
158 TypeError: cannot use 'in' operator to search for 'x' in 'y' Error, Errors, JavaScript, TypeError
TypeError
159 TypeError: cyclic object value Error, Errors, JavaScript, TypeError
TypeError
160 TypeError: invalid 'instanceof' operand 'x' Error, Errors, JavaScript, Reference, TypeError
TypeError
161 TypeError: invalid Array.prototype.sort argument Errors, JavaScript, TypeError
TypeError
162 TypeError: invalid arguments Error, Errors, JavaScript, TypeError
TypeError
163 TypeError: invalid assignment to const "x" Error, JavaScript, TypeError
TypeError
164 TypeError: property "x" is non-configurable and can't be deleted Errors, JavaScript, Strict Mode, TypeError
TypeError in strict mode only.
165 TypeError: setting getter-only property "x" Error, Errors, JavaScript, Strict Mode, TypeError
TypeError in strict mode only.
166 TypeError: variable "x" redeclares argument Errors, JavaScript, Strict Mode, TypeError
TypeError warning in strict mode only.
167 URIError: malformed URI sequence Error, Errors, JavaScript, URIError
URIError
168 Warning: -file- is being assigned a //# sourceMappingURL, but already has one Errors, JavaScript, Source maps, Warning
A warning. JavaScript execution won't be halted.
169 Warning: 08/09 is not a legal ECMA-262 octal constant Errors, JavaScript, SyntaxError, Warning
Warning. JavaScript execution won't be halted.
170 Warning: Date.prototype.toLocaleFormat is deprecated JavaScript, Warning
Warning. JavaScript execution won't be halted.
171 Warning: JavaScript 1.6's for-each-in loops are deprecated JavaScript, Warning
Warning
172 Warning: String.x is deprecated; use String.prototype.x instead JavaScript, Warning
Warning. JavaScript execution won't be halted.
173 Warning: expression closures are deprecated JavaScript, Warning
Warning. JavaScript execution won't be halted.
174 Warning: unreachable code after return statement JavaScript, Warning
Warning
175 JavaScript methods index JavaScript
This article entails a listing of all JavaScript methods documented on MDN sorted alphabetically.
176 JavaScript properties index JavaScript
This article entails a listing of all JavaScript properties documented on MDN sorted alphabetically.
177 Lexical grammar JavaScript, Keyword, Lexical Grammar, Literal
This page describes JavaScript's lexical grammar. The source text of ECMAScript scripts gets scanned from left to right and is converted into a sequence of input elements which are tokens, control characters, line terminators, comments or white space. ECMAScript also defines certain keywords and literals and has rules for automatic insertion of semicolons to end statements.
178 Standard built-in objects JavaScript, Overview, Reference
This chapter documents all of JavaScript's standard, built-in objects, including their methods and properties.
179 Array Array, Example, Global Objects, JavaScript, Reference
The JavaScript Array class is a global object that is used in the construction of arrays; which are high-level, list-like objects.
180 Array() constructor Constructor, JavaScript, Reference
The Array() constructor is used to create Array objects.
181 Array.from() Array, ECMAScript 2015, JavaScript, Method, Reference, polyfill
The Array.from() method creates a new, shallow-copied Array instance from an array-like or iterable object.
182 Array.isArray() Array, ECMAScript 5, JavaScript, Method, Reference, polyfill
The Array.isArray() method determines whether the passed value is an Array.
183 Array.length Array, JavaScript, Property, Reference
The length property of an object which is an instance of type Array sets or returns the number of elements in that array. The value is an unsigned, 32-bit integer that is always numerically greater than the highest index in the array.
184 Array.observe() Array, JavaScript, Method, Obsolete
The Array.observe() method was used for asynchronously observing changes to Arrays, similar to Object.observe() for objects. It provided a stream of changes in order of occurrence. It's equivalent to Object.observe() invoked with the accept type list ["add", "update", "delete", "splice"]. However, this API has been deprecated and removed from Browsers. You can use the more general Proxy object instead.
185 Array.of() Array, ECMAScript 2015, JavaScript, Method, polyfill
The Array.of() method creates a new Array instance from a variable number of arguments, regardless of number or type of the arguments.
186 Array.prototype.concat() Array, JavaScript, Method, Prototype, Reference, array.concat, concat
The concat() method is used to merge two or more arrays. This method does not change the existing arrays, but instead returns a new array.
187 Array.prototype.copyWithin() Array, ECMAScript 2015, JavaScript, Method, Prototype, Reference, polyfill
The copyWithin() method shallow copies part of an array to another location in the same array and returns it without modifying its length.
188 Array.prototype.entries() Array, ECMAScript 2015, Iterator, JavaScript, Method, Prototype
The entries() method returns a new Array Iterator object that contains the key/value pairs for each index in the array.
189 Array.prototype.every() Array, ECMAScript 5, JavaScript, Method, Prototype, polyfill
The every() method tests whether all elements in the array pass the test implemented by the provided function. It returns a Boolean value.
190 Array.prototype.fill() Array, ECMAScript 2015, JavaScript, Method, Prototype, polyfill
The fill() method fills (modifies) all the elements of an array from a start index (default zero) to an end index (default array length) with a static value. It returns the modified array.
191 Array.prototype.filter() Array, ECMAScript 5, JavaScript, Method, Prototype, Reference, polyfill
The filter() method creates a new array with all elements that pass the test implemented by the provided function.
192 Array.prototype.find() Array, ECMAScript 2015, JavaScript, Method, Prototype, Reference, polyfill
The find() method returns the value of the first element in the provided array that satisfies the provided testing function.
193 Array.prototype.findIndex() Array, ECMAScript 2015, JavaScript, Method, Prototype, Reference, polyfill
The findIndex() method returns the index of the first element in the array that satisfies the provided testing function. Otherwise, it returns -1, indicating that no element passed the test.
194 Array.prototype.flat() Array, JavaScript, Method, Prototype, Reference, flat
The flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.
195 Array.prototype.flatMap() Array, JavaScript, Map, Method, Prototype, Reference, flatMap
The flatMap() method first maps each element using a mapping function, then flattens the result into a new array. It is identical to a map() followed by a flat() of depth 1, but flatMap() is often quite useful, as merging both into one method is slightly more efficient.
196 Array.prototype.forEach() Array, ECMAScript 5, JavaScript, Method, Prototype, Reference
The forEach() method executes a provided function once for each array element.
197 Array.prototype.includes() Array, JavaScript, Method, Prototype, Reference, inArray, in_array, polyfill
The includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.
198 Array.prototype.indexOf() Array, JavaScript, Method, Prototype, Reference, indexof, polyfill
The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.
199 Array.prototype.join() Array, JavaScript, Method, Prototype, Reference
The join() method creates and returns a new string by concatenating all of the elements in an array (or an array-like object), separated by commas or a specified separator string. If the array has only one item, then that item will be returned without using the separator.
200 Array.prototype.keys() Array, ECMAScript 2015, Iterator, JavaScript, Method, Prototype, Reference
The keys() method returns a new Array Iterator object that contains the keys for each index in the array.
201 Array.prototype.lastIndexOf() Array, ECMAScript 5, JavaScript, Method, Prototype, polyfill
The lastIndexOf() method returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex.
202 Array.prototype.map() Array, ECMAScript 5, JavaScript, Method, Prototype, Reference, polyfill
The map() method creates a new array with the results of calling a provided function on every element in the calling array.
203 Array.prototype.pop() Array, JavaScript, Method, Prototype, Reference
The pop() method removes the last element from an array and returns that element. This method changes the length of the array.
204 Array.prototype.push() Array, JavaScript, Method, Prototype, Reference
The push() method adds one or more elements to the end of an array and returns the new length of the array.
205 Array.prototype.reduce() Array, Array method, ECMAScript 5, JavaScript, Method, Prototype, Reduce, Reference
The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in a single output value.
206 Array.prototype.reduceRight() Array, ECMAScript 5, JavaScript, Method, Prototype, polyfill
The reduceRight() method applies a function against an accumulator and each value of the array (from right-to-left) to reduce it to a single value.
207 Array.prototype.reverse() Array, JavaScript, Method, Prototype
The reverse() method reverses an array in place. The first array element becomes the last, and the last array element becomes the first.
208 Array.prototype.shift() Array, JavaScript, Method, Prototype, Reference
The shift() method removes the first element from an array and returns that removed element. This method changes the length of the array.
209 Array.prototype.slice() Array, JavaScript, Method, Prototype, Reference
The slice() method returns a shallow copy of a portion of an array into a new array object selected from begin to end (end not included) where begin and end represent the index of items in that array. The original array will not be modified.
210 Array.prototype.some() Array, ECMAScript 5, Example, JavaScript, Method, NeedsLiveSample, NeedsUpdate, Prototype, Reference
The some() method tests whether at least one element in the array passes the test implemented by the provided function. It returns a Boolean value.
211 Array.prototype.sort() Array, Array method, JavaScript, Method, Prototype, Sorting
The sort() method sorts the elements of an array in place and returns the sorted array. The default sort order is ascending, built upon converting the elements into strings, then comparing their sequences of UTF-16 code units values.
212 Array.prototype.splice() Array, JavaScript, Method, Prototype, Reference, remove, replace, splice
The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.
213 Array.prototype.toLocaleString() Array, Internationalization, JavaScript, Method, Prototype
The toLocaleString() method returns a string representing the elements of the array. The elements are converted to Strings using their toLocaleString methods and these Strings are separated by a locale-specific String (such as a comma “,”).
214 Array.prototype.toSource() Array, JavaScript, Method, Non-standard, Prototype, Reference
The toSource() method returns a string representing the source code of the array.
215 Array.prototype.toString() Array, JavaScript, Method, Prototype
The toString() method returns a string representing the specified array and its elements.
216 Array.prototype.unshift() Array, JavaScript, Method, Prototype, Reference
The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.
217 Array.prototype.values() Array, ECMAScript 2015, Iterator, JavaScript, Method, NeedsContent, NeedsExample, NeedsLiveSample, Prototype
The values() method returns a new Array Iterator object that contains the values for each index in the array.
218 Array.prototype[@@iterator]() Array, ECMAScript 2015, Iterator, JavaScript, Method, NeedsContent, NeedsExample, NeedsLiveSample, Prototype, Reference
The initial value of the @@iterator property is the same function object as the initial value of the values() property.
219 Array.prototype[@@unscopables] Array, ECMAScript 2015, JavaScript, Property, Prototype
The @@unscopable symbol property contains property names that were not included in the ECMAScript standard prior to the ES2015 version. These properties are excluded from with statement bindings.
220 Array.unobserve() Array, JavaScript, Method, Obsolete
The Array.unobserve() method was used to remove observers set by Array.observe(), but has been deprecated and removed from Browsers. You can use the more general Proxy object instead.
221 get Array[@@species] Array, JavaScript, Method, Prototype
The Array[@@species] accessor property returns the Array constructor.
222 ArrayBuffer ArrayBuffer, Constructor, JavaScript, TypedArrays
The ArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer.
223 ArrayBuffer.isView() ArrayBuffer, JavaScript, Method, TypedArrays
The ArrayBuffer.isView() method returns true if arg is one of the ArrayBuffer views, such as typed array objects or a DataView; false otherwise.
224 ArrayBuffer.prototype ArrayBuffer, JavaScript, Property
The ArrayBuffer.prototype property represents the prototype for the ArrayBuffer object.
225 ArrayBuffer.prototype.byteLength ArrayBuffer, JavaScript, Property, Prototype
The byteLength accessor property represents the length of an ArrayBuffer in bytes.
226 ArrayBuffer.prototype.slice() ArrayBuffer, JavaScript, Method, Prototype
The slice() method returns a new ArrayBuffer whose contents are a copy of this ArrayBuffer's bytes from begin, inclusive, up to end, exclusive.
227 ArrayBuffer.transfer() ArrayBuffer, Experimental, JavaScript, Method, Reference, TypedArrays
The static ArrayBuffer.transfer() method returns a new ArrayBuffer whose contents have been taken from the oldBuffer's data and then is either truncated or zero-extended by newByteLength. If newByteLength is undefined, the byteLength of the oldBuffer is used. This operation leaves oldBuffer in a detached state.
228 get ArrayBuffer[@@species] ArrayBuffer, JavaScript, Property, TypedArrays
The ArrayBuffer[@@species] accessor property returns the ArrayBuffer constructor.
229 AsyncFunction Constructor, Experimental, JavaScript, Reference
The AsyncFunction constructor creates a new async function object. In JavaScript, every asynchronous function is actually an AsyncFunction object.
230 AsyncFunction.prototype Experimental, JavaScript, Property, Prototype, Reference
The AsyncFunction.prototype property represents the AsyncFunction prototype object.
231 Atomics JavaScript, Shared Memory, Specifications
The Atomics object provides atomic operations as static methods. They are used with SharedArrayBuffer objects.
232 Atomics.add() Atomics, JavaScript, Method, Shared Memory
The static Atomics.add() method adds a given value at a given position in the array and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
233 Atomics.and() Atomics, JavaScript, Method, Shared Memory
The static Atomics.and() method computes a bitwise AND with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
234 Atomics.compareExchange() Atomics, JavaScript, Method, Shared Memory
The static Atomics.compareExchange() method exchanges a given replacement value at a given position in the array, if a given expected value equals the old value.  It returns the old value at that position whether it was equal to the expected value or not. This atomic operation guarantees that no other write happens until the modified value is written back.
235 Atomics.exchange() Atomics, JavaScript, Method, Shared Memory
The static Atomics.exchange() method stores a given value at a given position in the array and returns the old value at that position. This atomic operation guarantees that no other write happens between the read of the old value and the write of the new value.
236 Atomics.isLockFree() Atomics, JavaScript, Method, Shared Memory
The static Atomics.isLockFree() method is used to determine whether to use locks or atomic operations. It returns true, if the given size is one of the BYTES_PER_ELEMENT property of integer TypedArray types.
237 Atomics.load() Atomics, JavaScript, Method, Shared Memory
The static Atomics.load() method returns a value at a given position in the array.
238 Atomics.notify() Atomics, JavaScript, Method, Shared Memory
The static Atomics.notify() method notifies up some agents that are sleeping in the wait queue.
239 Atomics.or() Atomics, JavaScript, Method, Shared Memory
The static Atomics.or() method computes a bitwise OR with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
240 Atomics.store() Atomics, JavaScript, Method, Shared Memory
The static Atomics.store() method stores a given value at the given position in the array and returns that value.
241 Atomics.sub() Atomics, JavaScript, Method, Shared Memory
The static Atomics.sub() method substracts a given value at a given position in the array and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
242 Atomics.wait() Atomics, JavaScript, Method, Shared Memory
The static Atomics.wait() method verifies that a given position in an Int32Array still contains a given value and if so sleeps, awaiting a wakeup or a timeout. It returns a string which is either "ok", "not-equal", or "timed-out".
243 Atomics.xor() Atomics, JavaScript, Method, Shared Memory
The static Atomics.xor() method computes a bitwise XOR with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
244 BigInt BigInt, JavaScript, Reference
BigInt is a built-in object that provides a way to represent whole numbers larger than 253 - 1, which is the largest number JavaScript can reliably represent with the Number primitive. BigInt can be used for arbitrarily large integers.
245 BigInt() constructor BigInt, Constructor, JavaScript, Reference
The BigInt() constructor is used to create BigInt objects.
246 BigInt.asIntN() BigInt, JavaScript, Method, Reference, asIntN
The BigInt.asIntN static method is used to wrap a BigInt value to a signed integer between -2width-1 and 2width-1-1.
247 BigInt.asUintN() BigInt, JavaScript, Method, Reference, asUintN
The BigInt.asUintN static method is used to wrap a BigInt value to an unsigned integer between between 0 and 2width-1.
248 BigInt.prototype.toLocaleString() BigInt, Internationalization, Intl, JavaScript, Method, Prototype
The toLocaleString() method returns a string with a language-sensitive representation of this BigInt.
249 BigInt.prototype.toString() BigInt, JavaScript, Method, Prototype, toString()
The toString() method returns a string representing the specified BigInt object. The trailing "n" is not part of the string.
250 BigInt.prototype.valueOf() BigInt, JavaScript, Method, Prototype, valueOf()
The valueOf() method returns the wrapped primitive value of a BigInt object.
251 BigInt64Array BigInt, BigInt64Array, Constructor, JavaScript, Reference, TypedArray, TypedArrays
The BigInt64Array typed array represents an array of 64-bit signed integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0n. Once established, you can reference elements in the array using the object's methods, or by using standard array index syntax (that is, using bracket notation).
252 BigUint64Array BigInt, BigUInt64Array, Constructor, JavaScript, Reference, TypedArray, TypedArrays
The BigUint64Array typed array represents an array of 64-bit unsigned integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0n. Once established, you can reference elements in the array using the object's methods, or by using standard array index syntax (that is, using bracket notation).
253 Boolean Boolean, Constructor, JavaScript, Reference
The Boolean object is an object wrapper for a boolean value.
254 Boolean.prototype Boolean, JavaScript, Property, Prototype
The Boolean.prototype property represents the prototype for the Boolean constructor.
255 Boolean.prototype.toSource() Boolean, JavaScript, Method, Non-standard, Prototype
The toSource() method returns a string representing the source code of the object.
256 Boolean.prototype.toString() Boolean, JavaScript, Method, Prototype
The toString() method returns a string representing the specified Boolean object.
257 Boolean.prototype.valueOf() Boolean, JavaScript, Method, Prototype
The valueOf() method returns the primitive value of a Boolean object.
258 DataView Constructor, DataView, JavaScript, TypedArrays
The DataView view provides a low-level interface for reading and writing multiple number types in a binary ArrayBuffer, without having to care about the platform's endianness.
259 DataView.prototype DataView, JavaScript, Property
The DataView.prototype property represents the prototype for the DataView object.
260 DataView.prototype.buffer DataView, JavaScript, Property, Prototype, TypedArrays
The buffer accessor property represents the ArrayBuffer or SharedArrayBuffer referenced by the DataView at construction time.
261 DataView.prototype.byteLength DataView, JavaScript, Property, Prototype, TypedArrays
The byteLength accessor property represents the length (in bytes) of this view from the start of its ArrayBuffer or SharedArrayBuffer.
262 DataView.prototype.byteOffset DataView, JavaScript, Property, Prototype, TypedArrays
The byteOffset accessor property represents the offset (in bytes) of this view from the start of its ArrayBuffer or SharedArrayBuffer.
263 DataView.prototype.getBigInt64() BigInt, DataView, JavaScript, Method, Prototype, Reference, TypedArrays, getBigInt64()
The getBigInt64() method gets a signed 64-bit integer (long long) at the specified byte offset from the start of the DataView.
264 DataView.prototype.getBigUint64() BigInt, DataView, JavaScript, Method, Prototype, Reference, TypedArrays, getBigUint64
The getBigUint64() method gets an unsigned 64-bit integer (unsigned long long) at the specified byte offset from the start of the DataView.
265 DataView.prototype.getFloat32() DataView, JavaScript, Method, Prototype, TypedArrays
The getFloat32() method gets a signed 32-bit float (float) at the specified byte offset from the start of the DataView.
266 DataView.prototype.getFloat64() DataView, JavaScript, Method, Prototype, TypedArrays
The getFloat64() method gets a signed 64-bit float (double) at the specified byte offset from the start of the DataView.
267 DataView.prototype.getInt16() DataView, JavaScript, Method, Prototype, TypedArrays
The getInt16() method gets a signed 16-bit integer (short) at the specified byte offset from the start of the DataView.
268 DataView.prototype.getInt32() DataView, JavaScript, Method, Prototype, TypedArrays
The getInt32() method gets a signed 32-bit integer (long) at the specified byte offset from the start of the DataView.
269 DataView.prototype.getInt8() DataView, JavaScript, Method, Prototype, TypedArrays
The getInt8() method gets a signed 8-bit integer (byte) at the specified byte offset from the start of the DataView.
270 DataView.prototype.getUint16() DataView, JavaScript, Method, Prototype, TypedArrays
The getUint16() method gets an unsigned 16-bit integer (unsigned short) at the specified byte offset from the start of the DataView.
271 DataView.prototype.getUint32() DataView, JavaScript, Method, Prototype, TypedArrays
The getUint32() method gets an unsigned 32-bit integer (unsigned long) at the specified byte offset from the start of the DataView.
272 DataView.prototype.getUint8() DataView, JavaScript, Method, Prototype, TypedArrays
The getUint8() method gets an unsigned 8-bit integer (unsigned byte) at the specified byte offset from the start of the DataView.
273 DataView.prototype.setBigInt64() BigInt, DataView, JavaScript, Method, Prototype, Reference, TypedArrays, setBigInt64
The setBigInt64() method stores a signed 64-bit integer (long long) value at the specified byte offset from the start of the DataView.
274 DataView.prototype.setBigUint64() BigInt, DataView, JavaScript, Method, Prototype, Reference, TypedArrays, setBigUint64
The setBigUint64() method stores an unsigned 64-bit integer (unsigned long long) value at the specified byte offset from the start of the DataView.
275 DataView.prototype.setFloat32() DataView, JavaScript, Method, Prototype, TypedArrays
The setFloat32() method stores a signed 32-bit float (float) value at the specified byte offset from the start of the DataView.
276 DataView.prototype.setFloat64() DataView, JavaScript, Method, Prototype, TypedArrays
The setFloat64() method stores a signed 64-bit float (double) value at the specified byte offset from the start of the DataView.
277 DataView.prototype.setInt16() DataView, JavaScript, Method, Prototype, TypedArrays
The setInt16() method stores a signed 16-bit integer (short) value at the specified byte offset from the start of the DataView.
278 DataView.prototype.setInt32() DataView, JavaScript, Method, Prototype, TypedArrays
The setInt32() method stores a signed 32-bit integer (long) value at the specified byte offset from the start of the DataView.
279 DataView.prototype.setInt8() DataView, JavaScript, Method, Prototype, TypedArrays
The setInt8() method stores a signed 8-bit integer (byte) value at the specified byte offset from the start of the DataView.
280 DataView.prototype.setUint16() DataView, JavaScript, Method, Prototype, TypedArrays
The setUint16() method stores an unsigned 16-bit integer (unsigned short) value at the specified byte offset from the start of the DataView.
281 DataView.prototype.setUint32() DataView, JavaScript, Method, Prototype, TypedArrays
The setUint32() method stores an unsigned 32-bit integer (unsigned long) value at the specified byte offset from the start of the DataView.
282 DataView.prototype.setUint8() DataView, JavaScript, Method, Prototype, TypedArrays
The setUint8() method stores an unsigned 8-bit integer (byte) value at the specified byte offset from the start of the DataView.
283 Date Date, Epoch, JavaScript, Time, Unix Epoch, timeStamp
Creates a JavaScript Date instance that represents a single moment in time in a platform-independent format.
284 Date.UTC() Date, JavaScript, Method, Reference
The Date.UTC() method accepts parameters similar to the Date constructor, but treats them as UTC. It returns the number of milliseconds since January 1, 1970, 00:00:00 UTC.
285 Date.now() Date, JavaScript, MakeBrowserAgnostic, Method, Reference, polyfill
The Date.now() method returns the number of milliseconds elapsed since January 1, 1970 00:00:00 UTC.
286 Date.parse() Date, JavaScript, Method, Reference
The Date.parse() method parses a string representation of a date, and returns the number of milliseconds since January 1, 1970, 00:00:00 UTC or NaN if the string is unrecognized or, in some cases, contains illegal date values (e.g. 2015-02-31).
287 Date.prototype Date, JavaScript, Property, Prototype, Reference
The Date.prototype property represents the prototype for the Date constructor.
288 Date.prototype.getDate() Date, JavaScript, Method, Prototype, Reference
The getDate() method returns the day of the month for the specified date according to local time.
289 Date.prototype.getDay() Date, JavaScript, Method, Prototype, Reference
The getDay() method returns the day of the week for the specified date according to local time, where 0 represents Sunday.
290 Date.prototype.getFullYear() Date, JavaScript, Method, Prototype, Reference
The getFullYear() method returns the year of the specified date according to local time.
291 Date.prototype.getHours() Date, JavaScript, Method, Prototype, Reference
The getHours() method returns the hour for the specified date, according to local time.
292 Date.prototype.getMilliseconds() Date, JavaScript, Method, Prototype, Reference
The getMilliseconds() method returns the milliseconds in the specified date according to local time.
293 Date.prototype.getMinutes() Date, JavaScript, Method, Prototype, Reference
The getMinutes() method returns the minutes in the specified date according to local time.
294 Date.prototype.getMonth() Date, JavaScript, Method, Prototype, Reference
The getMonth() method returns the month in the specified date according to local time, as a zero-based value (where zero indicates the first month of the year).
295 Date.prototype.getSeconds() Date, JavaScript, Method, Prototype, Reference
The getSeconds() method returns the seconds in the specified date according to local time.
296 Date.prototype.getTime() Date, JavaScript, Method, Prototype, Reference
The getTime() method returns the number of milliseconds* since the Unix Epoch.
297 Date.prototype.getTimezoneOffset() Date, JavaScript, Method, Prototype, Reference
The getTimezoneOffset() method returns the time zone difference, in minutes, from current locale (host system settings) to UTC.
298 Date.prototype.getUTCDate() Date, JavaScript, Method, Prototype, Reference
The getUTCDate() method returns the day (date) of the month in the specified date according to universal time.
299 Date.prototype.getUTCDay() Date, JavaScript, Method, Prototype, Reference
The getUTCDay() method returns the day of the week in the specified date according to universal time, where 0 represents Sunday.
300 Date.prototype.getUTCFullYear() Date, JavaScript, Method, Prototype, Reference
The getUTCFullYear() method returns the year in the specified date according to universal time.
301 Date.prototype.getUTCHours() Date, JavaScript, Method, Prototype, Reference
The getUTCHours() method returns the hours in the specified date according to universal time.
302 Date.prototype.getUTCMilliseconds() Date, JavaScript, Method, Prototype, Reference
The getUTCMilliseconds() method returns the milliseconds portion of the time object's value.
303 Date.prototype.getUTCMinutes() Date, JavaScript, Method, Prototype, Reference
The getUTCMinutes() method returns the minutes in the specified date according to universal time.
304 Date.prototype.getUTCMonth() Date, JavaScript, Method, Prototype, Reference
The getUTCMonth() returns the month of the specified date according to universal time, as a zero-based value (where zero indicates the first month of the year).
305 Date.prototype.getUTCSeconds() Date, JavaScript, Method, Prototype, Reference
The getUTCSeconds() method returns the seconds in the specified date according to universal time.
306 Date.prototype.getYear() Date, Deprecated, JavaScript, Method, Prototype, Reference
The getYear() method returns the year in the specified date according to local time. Because getYear() does not return full years ("year 2000 problem"), it is no longer used and has been replaced by the getFullYear() method.
307 Date.prototype.setDate() Date, JavaScript, Method, Prototype, Reference
The setDate() method sets the day of the Date object relative to the beginning of the currently set month.
308 Date.prototype.setFullYear() Date, JavaScript, Method, Prototype, Reference
The setFullYear() method sets the full year for a specified date according to local time. Returns new timestamp.
309 Date.prototype.setHours() Date, JavaScript, Method, Prototype, Reference
The setHours() method sets the hours for a specified date according to local time, and returns the number of milliseconds since January 1, 1970 00:00:00 UTC until the time represented by the updated Date instance.
310 Date.prototype.setMilliseconds() Date, JavaScript, Method, Prototype, Reference
The setMilliseconds() method sets the milliseconds for a specified date according to local time.
311 Date.prototype.setMinutes() Date, JavaScript, Method, Prototype, Reference
The setMinutes() method sets the minutes for a specified date according to local time.
312 Date.prototype.setMonth() Date, JavaScript, Method, Prototype, Reference
The setMonth() method sets the month for a specified date according to the currently set year.
313 Date.prototype.setSeconds() Date, JavaScript, Method, Prototype, Reference
The setSeconds() method sets the seconds for a specified date according to local time.
314 Date.prototype.setTime() Date, JavaScript, Method, Prototype, Reference
The setTime() method sets the Date object to the time represented by a number of milliseconds since January 1, 1970, 00:00:00 UTC.
315 Date.prototype.setUTCDate() Date, JavaScript, Method, Prototype, Reference
The setUTCDate() method sets the day of the month for a specified date according to universal time.
316 Date.prototype.setUTCFullYear() Date, JavaScript, Method, Prototype, Reference
The setUTCFullYear() method sets the full year for a specified date according to universal time.
317 Date.prototype.setUTCHours() Date, JavaScript, Method, Prototype, Reference
The setUTCHours() method sets the hour for a specified date according to universal time, and returns the number of milliseconds since  January 1, 1970 00:00:00 UTC until the time represented by the updated Date instance.
318 Date.prototype.setUTCMilliseconds() Date, JavaScript, Method, Prototype, Reference
The setUTCMilliseconds() method sets the milliseconds for a specified date according to universal time.
319 Date.prototype.setUTCMinutes() Date, JavaScript, Method, Prototype, Reference
The setUTCMinutes() method sets the minutes for a specified date according to universal time.
320 Date.prototype.setUTCMonth() Date, JavaScript, Method, Prototype, Reference
The setUTCMonth() method sets the month for a specified date according to universal time.
321 Date.prototype.setUTCSeconds() Date, JavaScript, Method, Prototype, Reference
The setUTCSeconds() method sets the seconds for a specified date according to universal time.
322 Date.prototype.setYear() Date, Deprecated, JavaScript, Method, Prototype, Reference
The setYear() method sets the year for a specified date according to local time. Because setYear() does not set full years ("year 2000 problem"), it is no longer used and has been replaced by the setFullYear() method.
323 Date.prototype.toDateString() Date, JavaScript, Method, Prototype, Reference
The toDateString() method returns the date portion of a Date object in English in the following format separated by spaces:
324 Date.prototype.toGMTString() Date, Deprecated, JavaScript, Method, Prototype, Reference
The toGMTString() method converts a date to a string, using Internet Greenwich Mean Time (GMT) conventions. The exact format of the value returned by toGMTString() varies according to the platform and browser, in general it should represent a human readable date string.
325 Date.prototype.toISOString() Date, JavaScript, Method, Prototype, Reference, polyfill
The toISOString() method returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long (YYYY-MM-DDTHH:mm:ss.sssZ or ±YYYYYY-MM-DDTHH:mm:ss.sssZ, respectively). The timezone is always zero UTC offset, as denoted by the suffix "Z".
326 Date.prototype.toJSON() Date, JavaScript, Method, Prototype, Reference
The toJSON() method returns a string representation of the Date object.
327 Date.prototype.toLocaleDateString() Date, IANA Timezone Format, Internationalization, JavaScript, Method, Prototype, Reference
The toLocaleDateString() method returns a string with a language sensitive representation of the date portion of this date. The new locales and options arguments let applications specify the language whose formatting conventions should be used and allow to customize the behavior of the function. In older implementations, which ignore the locales and options arguments, the locale used and the form of the string returned are entirely implementation dependent.
328 Date.prototype.toLocaleFormat() Date, JavaScript, Method, Non-standard, Prototype, Reference
The non-standard toLocaleFormat() method converts a date to a string using the specified formatting. Intl.DateTimeFormat is an alternative to format dates in a standards-compliant way. See also the newer version of Date.prototype.toLocaleDateString().
329 Date.prototype.toLocaleString() Date, Internationalization, JavaScript, Method, Prototype, Reference
The toLocaleString() method returns a string with a language sensitive representation of this date. The new locales and options arguments let applications specify the language whose formatting conventions should be used and customize the behavior of the function. In older implementations, which ignore the locales and options arguments, the locale used and the form of the string returned are entirely implementation dependent.
330 Date.prototype.toLocaleTimeString() Date, Internationalization, JavaScript, Method, Prototype, Reference
The toLocaleTimeString() method returns a string with a language sensitive representation of the time portion of this date. The new locales and options arguments let applications specify the language whose formatting conventions should be used and customize the behavior of the function. In older implementations, which ignore the locales and options arguments, the locale used and the form of the string returned are entirely implementation dependent.
331 Date.prototype.toSource() Date, JavaScript, Method, Prototype, Reference
The toSource() method returns a string representing the source code of the object.
332 Date.prototype.toString() Date, JavaScript, Method, Prototype, Reference
The toString() method returns a string representing the specified Date object.
333 Date.prototype.toTimeString() Date, JavaScript, Method, Prototype, Reference
The toTimeString() method returns the time portion of a Date object in human readable form in American English.
334 Date.prototype.toUTCString() Date, JavaScript, Method, Prototype, Reference
The toUTCString() method converts a date to a string, using the UTC time zone.
335 Date.prototype.valueOf() Date, JavaScript, Method, Prototype, Reference
The valueOf() method returns the primitive value of a Date object.
336 Date.prototype[@@toPrimitive] Date, JavaScript, Method, Prototype, Reference
The [@@toPrimitive]() method converts a Date object to a primitive value.
337 Error Error, JavaScript, Reference
The Error constructor creates an error object.
338 Error.prototype Error, JavaScript, Property
The Error.prototype property represents the prototype for the Error constructor.
339 Error.prototype.columnNumber Error, JavaScript, Non-standard, Property, Prototype
The columnNumber property contains the column number in the line of the file that raised this error.
340 Error.prototype.fileName Error, JavaScript, Non-standard, Property, Prototype
The fileName property contains the path to the file that raised this error.
341 Error.prototype.lineNumber Error, JavaScript, Non-standard, Property, Prototype, Reference
The lineNumber property contains the line number in the file that raised this error.
342 Error.prototype.message Error, JavaScript, Property, Prototype
The message property is a human-readable description of the error.
343 Error.prototype.name Error, JavaScript, Property, Prototype
The name property represents a name for the type of error. The initial value is "Error".
344 Error.prototype.stack Error, JavaScript, Non-standard, Property, Prototype, Reference
The non-standard stack property of Error objects offer a trace of which functions were called, in what order, from which line and file, and with what arguments. The stack string proceeds from the most recent calls to earlier ones, leading back to the original global scope call.
345 Error.prototype.toSource() Error, JavaScript, Method, Non-standard, Prototype
The toSource() method returns code that could eval to the same error.
346 Error.prototype.toString() Error, JavaScript, Method, Prototype
The toString() method returns a string representing the specified Error object.
347 EvalError Error, EvalError, JavaScript, Reference
The EvalError object indicates an error regarding the global eval() function. This exception is not thrown by JavaScript anymore, however the EvalError object remains for compatibility.
348 EvalError.prototype Error, EvalError, JavaScript, Property
The EvalError.prototype property represents the prototype of the EvalError constructor.
349 Float32Array Constructor, JavaScript, TypedArray, TypedArrays
The Float32Array typed array represents an array of 32-bit floating point numbers (corresponding to the C float data type) in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
350 Float64Array Constructor, JavaScript, TypedArray, TypedArrays
The Float64Array typed array represents an array of 64-bit floating point numbers (corresponding to the C double data type) in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
351 Function Constructor, Function, JavaScript
The Function constructor creates a new Function object. Calling the constructor directly can create functions dynamically, but suffers from security and similar (but far less significant) performance issues to eval. However, unlike eval, the Function constructor creates functions which execute in the global scope only.
352 Function.arguments Deprecated, Function, JavaScript, Property, arguments
The function.arguments property refers to an an array-like object corresponding to the arguments passed to a function. Use the simple variable arguments instead. This property is forbidden in strict mode.
353 Function.arity Function, JavaScript, Obsolete, Property, Unimplemented
Implemented in JavaScript 1.2. Deprecated in JavaScript 1.4.
354 Function.caller Function, JavaScript, Non-standard, Property
The function.caller property returns the function that invoked the specified function. This property is forbidden in strict mode.
355 Function.displayName Function, JavaScript, Non-standard, Property
The function.displayName property returns the display name of the function.
356 Function.length Function, JavaScript, Property
The length property indicates the number of parameters expected by the function.
357 Function.name ECMAScript 2015, Function, JavaScript, Property
A Function object's read-only name property indicates the function's name as specified when it was created, or it may be rather anonymous or ''(an empty string) for functions created anonymously.
358 Function.prototype Function, JavaScript, Property, Prototype
The Function.prototype property represents the Function prototype object.
359 Function.prototype.apply() Function, JavaScript, Method, Reference
The apply() method calls a function with a given this value, and arguments provided as an array (or an array-like object).
360 Function.prototype.bind() ECMAScript 2015, ECMAScript 5, Function, JavaScript, Method, polyfill
The bind() method creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.
361 Function.prototype.call() Function, JavaScript, Method
The call() method calls a function with a given this value and arguments provided individually.
362 Function.prototype.isGenerator() Function, JavaScript, Method, Non-standard, Obsolete
The non-standard isGenerator() method used to determine whether or not a function is a generator. It has been removed from Firefox starting with version 58.
363 Function.prototype.toSource() Function, JavaScript, Method, Non-standard
The toSource() method returns a string representing the source code of the object.
364 Function.prototype.toString() Function, JavaScript, Method, Prototype
The toString() method returns a string representing the source code of the function.
365 Generator ECMAScript 2015, Generator, JavaScript, Legacy Generator, Legacy Iterator, Reference
The Generator object is returned by a generator function and it conforms to both the iterable protocol and the iterator protocol.
366 Generator.prototype.next() ECMAScript 2015, Generator, JavaScript, Method, Prototype, Reference
The next() method returns an object with two properties done and value. You can also provide a parameter to the next method to send a value to the generator.
367 Generator.prototype.return() ECMAScript 2015, Generator, JavaScript, Method, Prototype, Reference
The return() method returns the given value and finishes the generator.
368 Generator.prototype.throw() ECMAScript 2015, Generator, JavaScript, Method, Prototype, Reference
The throw() method resumes the execution of a generator by throwing an error into it and returns an object with two properties done and value.
369 GeneratorFunction Constructor, ECMAScript 2015, GeneratorFunction, Iterator, JavaScript, Reference
The GeneratorFunction constructor creates a new generator function object. In JavaScript every generator function is actually a GeneratorFunction object.
370 GeneratorFunction.prototype ECMAScript 2015, GeneratorFunction, Iterator, JavaScript, Property, Prototype, Reference
The GeneratorFunction.prototype property represents the GeneratorFunction prototype object.
371 Infinity JavaScript
The global Infinity property is a numeric value representing infinity.
372 Int16Array Constructor, JavaScript, TypedArray, TypedArrays
The Int16Array typed array represents an array of twos-complement 16-bit signed integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
373 Int32Array Constructor, JavaScript, TypedArray, TypedArrays
The Int32Array typed array represents an array of twos-complement 32-bit signed integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
374 Int8Array Constructor, Int8Array, JavaScript, TypedArray, TypedArrays
The Int8Array typed array represents an array of twos-complement 8-bit signed integers. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
375 InternalError Error, InternalError, JavaScript
The InternalError object indicates an error that occurred internally in the JavaScript engine. For example: "InternalError: too much recursion".
376 InternalError.prototype Error, InternalError, JavaScript, Property
The InternalError.prototype property represents the prototype of the InternalError constructor.
377 Intl Internationalization, Intl, JavaScript
The Intl object is the namespace for the ECMAScript Internationalization API, which provides language sensitive string comparison, number formatting, and date and time formatting. The Intl object provides access to several constructors as well as functionality common to the internationalization constructors and other language sensitive functions.
378 Intl.getCanonicalLocales() Internationalization, Intl, JavaScript, Method
The Intl.getCanonicalLocales() method returns an array containing the canonical locale names. Duplicates will be omitted and elements will be validated as structurally valid language tags.
379 Intl.Collator Collator, Constructor, Internationalization, Intl, JavaScript
The Intl.Collator object is a constructor for collators, objects that enable language sensitive string comparison.
380 Intl.Collator.prototype Collator, Internationalization, Intl, JavaScript, Property, Prototype
The Intl.Collator.prototype property represents the prototype object for the Intl.Collator constructor.
381 Intl.Collator.prototype.compare() Collator, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.Collator.prototype.compare() method compares two strings according to the sort order of this Collator object.
382 Intl.Collator.prototype.resolvedOptions() Collator, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.Collator.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and collation options computed during initialization of this Collator object.
383 Intl.Collator.supportedLocalesOf() Collator, Internationalization, Intl, JavaScript, Method
The Intl.Collator.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in collation without having to fall back to the runtime's default locale.
384 Intl.DateTimeFormat DateTimeFormat, Internationalization, Intl, JavaScript, Reference
The Intl.DateTimeFormat object is a constructor for objects that enable language-sensitive date and time formatting.
385 Intl.DateTimeFormat.prototype DateTimeFormat, Internationalization, Intl, JavaScript, Property, Prototype
The Intl.DateTimeFormat.prototype property represents the prototype object for the Intl.DateTimeFormat constructor.
386 Intl.DateTimeFormat.prototype.format() DateTimeFormat, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.DateTimeFormat.prototype.format() method formats a date according to the locale and formatting options of this Intl.DateTimeFormat object.
387 Intl.DateTimeFormat.prototype.formatRange() JavaScript, Method
The Intl.DateTimeFormat.prototype.formatRange() formats a date range in the most concise way based on the locale and options provided when instantiating Intl.DateTimeFormat object.
388 Intl.DateTimeFormat.prototype.formatRangeToParts() Internationalization, JavaScript, Localization, i18n
The Intl.DateTimeFormat.prototype.formatRangeToParts() method allows locale-specific tokens representing each part of the formatted date range produced by DateTimeFormat formatters.
389 Intl.DateTimeFormat.prototype.formatToParts() DateTimeFormat, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.DateTimeFormat.prototype.formatToParts() method allows locale-aware formatting of strings produced by DateTimeFormat formatters.
390 Intl.DateTimeFormat.prototype.resolvedOptions() DateTimeFormat, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.DateTimeFormat.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and date and time formatting options computed during initialization of this DateTimeFormat object.
391 Intl.DateTimeFormat.supportedLocalesOf() DateTimeFormat, Internationalization, Intl, JavaScript, Method, Prototype
The Intl.DateTimeFormat.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in date and time formatting without having to fall back to the runtime's default locale.
392 Intl.DisplayNames Example, JavaScript, Reference
No summary!
393 Intl.ListFormat Experimental, Internationalization, Intl, JavaScript, ListFormat
The Intl.ListFormat object is a constructor for objects that enable language-sensitive list formatting.
394 Intl.ListFormat.prototype Internationalization, Intl, JavaScript, ListFormat, Property, Prototype
See ListFormat for a description of Intl.ListFormat instances.
395 Intl.ListFormat.supportedLocalesOf() Internationalization, Intl, JavaScript, ListFormat, Method, supportedLocalesOf
The Intl.ListFormat.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in date and time formatting without having to fall back to the runtime's default locale.
396 Intl​.ListFormat.prototype​.format() Internationalization, Intl, JavaScript, ListFormat, Method, Prototype
The format() method returns a string that has been formatted based on parameters provided in the Intl.ListFormat object. The locales and options parameters customize the behavior of format() and let applications specify the language conventions that should be used to format the list.
397 Intl​.List​Format​.prototype​.formatToParts() Internationalization, Intl, JavaScript, ListFormat, Method, Prototype
The Intl.ListFormat.prototype.formatToParts() method returns an Array of objects representing the different components that can be used to format a list of values in a locale-aware fashion.
398 Intl​.List​Format​.prototype​.resolvedOptions() Internationalization, Intl, JavaScript, ListFormat, Method, Prototype
The Intl.ListFormat.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and style formatting options computed during the construction of the current ListFormat object.
399 Intl.Locale Internationalization, Intl, JavaScript, Reference
The Intl.Locale constructor is a standard built-in property of the Intl object that represents a Unicode locale identifier.
400 Intl.Locale.prototype Intl.Locale, Intl.Locale.prototype, JavaScript, Language, Prototype, Script, caseFirst, collation, hourCycle, region, toString
The Intl.Locale.prototype property represents the prototype object for the Intl.Locale constructor.
401 Intl.Locale.prototype.baseName Internationalization, JavaScript
The Intl.Locale.prototype.baseName property returns a substring of the Locale's string representation, containing core information about the Locale.
402 Intl.Locale.prototype.calendar Internationalization, JavaScript
The Intl.Locale.prototype.calendar property is an accessor property which returns the type of calendar used in the Locale.
403 Intl.Locale.prototype.caseFirst Internationalization, JavaScript
The Intl.Locale.prototype.caseFirst property is an accessor property that returns whether case is taken into account for the locale's collation rules.
404 Intl.Locale.prototype.collation Internationalization, JavaScript, Reference
The Intl.Locale.prototype.collation property is an accessor property that returns the collation type for the Locale, which is used to order strings according to the locale's rules.
405 Intl.Locale.prototype.hourCycle Internationalization, JavaScript
The Intl.Locale.prototype.hourCycle property is an accessor property that returns the time keeping format convention used by the locale.
406 Intl.Locale.prototype.language Internationalization, JavaScript
The Intl.Locale.prototype.language property is an accessor property that returns the language associated with the locale.
407 Intl.Locale.prototype.maximize() Internationaliztion, Intl, JavaScript, Reference
The Intl.Locale.prototype.maximize() method gets the most likely values for the language, script, and region of the locale based on existing values.
408 Intl.Locale.prototype.minimize() Internationalization, Intl, JavaScript, Reference
The Intl.Locale.prototype.minimize() method attempts to remove information about the locale that would be added by calling Locale.maximize(). 
409 Intl.Locale.prototype.numberingSystem Internationalization, JavaScript
The Intl.Locale.prototype.numberingSystem property is an accessor property that returns the numeral system used by the locale.
410 Intl.Locale.prototype.numeric Internationalization, JavaScript
The Intl.Locale.prototype.numeric property is an accessor property that returns whether the locale has special collation handling for numeric characters.
411 Intl.Locale.prototype.region Internationalization, JavaScript
The Intl.Locale.prototype.region property is an accessor property that returns the region of the world (usually a country) associated with the locale.
412 Intl.Locale.prototype.script Internationalization, JavaScript
The Intl.Locale.prototype.script property is an accessor property which returns the script used for writing the particular language used in the locale.
413 Intl.Locale.prototype.toString() Intl.Locale, Intl.Locale.prototype, Intl.Locale.prototype.toString, JavaScript, toString
The Intl.Locale.prototype.toString() returns the Locale's full locale identifier string.
414 Intl.NumberFormat Internationalization, Intl, JavaScript, NumberFormat, Reference
The Intl.NumberFormat object is a constructor for objects that enable language sensitive number formatting.
415 Intl.NumberFormat.prototype Internationalization, Intl, JavaScript, NumberFormat, Property, Prototype
The Intl.NumberFormat.prototype property represents the prototype object for the Intl.NumberFormat constructor.
416 Intl.NumberFormat.prototype.format() Internationalization, Intl, JavaScript, Method, NumberFormat, Prototype
The Intl.NumberFormat.prototype.format() method formats a number according to the locale and formatting options of this NumberFormat object.
417 Intl.NumberFormat.prototype.formatToParts() Internationalization, Intl, JavaScript, Method, NumberFormat, Prototype
The Intl.Numberformat.prototype.formatToParts() method allows locale-aware formatting of strings produced by NumberTimeFormat formatters.
418 Intl.NumberFormat.prototype.resolvedOptions() Internationalization, Intl, JavaScript, Method, NumberFormat, Prototype
The Intl.NumberFormat.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and number formatting options computed during initialization of this NumberFormat object.
419 Intl.NumberFormat.supportedLocalesOf() Internationalization, Intl, JavaScript, Method, NumberFormat
The Intl.NumberFormat.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in number formatting without having to fall back to the runtime's default locale.
420 Intl.PluralRules Internationalization, Intl, JavaScript, PluralRules
The Intl.PluralRules object is a constructor for objects that enable plural sensitive formatting and plural language rules.
421 Intl.PluralRules.prototype Internationalization, Intl, JavaScript, Property, Prototype
The Intl.PluralRules.prototype property represents the prototype object for the Intl.PluralRules constructor.
422 Intl.PluralRules.prototype.resolvedOptions() Internationalization, Intl, JavaScript, Method, PluralRules, Prototype
The Intl.PluralRules.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and plural formatting options computed during initialization of this PluralRules object.
423 Intl.PluralRules.select() Internationalization, Intl, JavaScript, Method, PluralRules
The Intl.PluralRules.prototype.select method returns a String indicating which plural rule to use for locale-aware formatting.
424 Intl.PluralRules.supportedLocalesOf() Internationalization, Intl, JavaScript, Method, PluralRules
The Intl.PluralRules.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in plural formatting without having to fall back to the runtime's default locale.
425 Intl.RelativeTimeFormat Internationalization, Intl, JavaScript, RelativeTimeFormat
The Intl.RelativeTimeFormat object is a constructor for objects that enable language-sensitive relative time formatting.
426 Intl.RelativeTimeFormat.prototype IntI, Internationalization, JavaScript, Property, Reference, RelativeTimeFormat
The Intl.RelativeTimeFormat.prototype property represents the prototype object for the Intl.RelativeTimeFormat constructor.
427 Intl.RelativeTimeFormat.prototype.format() IntI, Internationalization, JavaScript, Method, Reference, RelativeTimeFormat
The Intl.RelativeTimeFormat.prototype.format() method formats a value and unit according to the locale and formatting options of this RelativeTimeFormat object.
428 Intl.RelativeTimeFormat.prototype.formatToParts() Internationalization, Intl, JavaScript, Method, Prototype, RelativeTimeFormat
The Intl.RelativeTimeFormat.prototype.formatToParts() method returns an Array of objects representing the relative time format in parts that can be used for custom locale-aware formatting.
429 Intl.RelativeTimeFormat.prototype.resolvedOptions() Internationalization, Intl, JavaScript, Method, Prototype, RelativeTimeFormat
The Intl.RelativeTimeFormat.prototype.resolvedOptions() method returns a new object with properties reflecting the locale and relative time formatting options computed during initialization of this RelativeTimeFormat object.
430 Intl.RelativeTimeFormat.supportedLocalesOf() IntI, Internationalization, JavaScript, Method, Reference, RelativeTimeFormat
The Intl.RelativeTimeFormat.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in date and time formatting without having to fall back to the runtime's default locale.
431 JSON JSON, JavaScript, Object, Reference
The JSON object contains methods for parsing JavaScript Object Notation (JSON) and converting values to JSON. It can't be called or constructed, and aside from its two method properties, it has no interesting functionality of its own.
432 JSON.parse() ECMAScript 5, JSON, JavaScript, Method, Reference
The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.
433 JSON.stringify() JSON, JavaScript, Method, Objects, Reference, stringify
The JSON.stringify() method converts a JavaScript object or value to a JSON string, optionally replacing values if a replacer function is specified or optionally including only the specified properties if a replacer array is specified.
434 Map ECMAScript 2015, JavaScript, Map, Reference
The Map object holds key-value pairs and remembers the original insertion order of the keys.
435 Map.prototype ECMAScript 2015, JavaScript, Map, Property, Reference
The Map.prototype property represents the prototype for the Map constructor.
436 Map.prototype.clear() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The clear() method removes all elements from a Map object.
437 Map.prototype.delete() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The delete() method removes the specified element from a Map object by key.
438 Map.prototype.entries() ECMAScript 2015, Iterator, JavaScript, Map, Method, Prototype
The entries() method returns a new Iterator object that contains the [key, value] pairs for each element in the Map object in insertion order.
439 Map.prototype.forEach() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The forEach() method executes a provided function once per each key/value pair in the Map object, in insertion order.
440 Map.prototype.get() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The get() method returns a specified element from a Map object.
441 Map.prototype.has() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The has() method returns a boolean indicating whether an element with the specified key exists or not.
442 Map.prototype.keys() ECMAScript 2015, Iterator, JavaScript, Map, Method, Prototype
The keys() method returns a new Iterator object that contains the keys for each element in the Map object in insertion order.
443 Map.prototype.set() ECMAScript 2015, JavaScript, Map, Method, Prototype, Reference
The set() method adds or updates an element with a specified key and a value to a Map object.
444 Map.prototype.size ECMAScript 2015, JavaScript, Map, Property
The size accessor property returns the number of elements in a Map object.
445 Map.prototype.values() ECMAScript 2015, Iterator, JavaScript, Map, Method, Prototype
The values() method returns a new Iterator object that contains the values for each element in the Map object in insertion order.
446 Map.prototype[@@iterator]() ECMAScript 2015, Iterator, JavaScript, Map, Method, Prototype, Reference
The initial value of the @@iterator property is the same function object as the initial value of the entries method.
447 Map.prototype[@@toStringTag] ECMAScript 2015, JavaScript, Map, Property, Prototype, Reference
The Map[@@toStringTag] property has an initial value of "Map".
448 get Map[@@species] ECMAScript 2015, JavaScript, Map, Property
The Map[@@species] accessor property returns the Map constructor.
449 Math JavaScript, Math, Reference
Math is a built-in object that has properties and methods for mathematical constants and functions. Not a function object.
450 Math.E JavaScript, Math, Property, Reference
The Math.E property represents the base of natural logarithms, e, approximately 2.718.
451 Math.LN10 JavaScript, Math, Property, Reference
The Math.LN10 property represents the natural logarithm of 10, approximately 2.302:
452 Math.LN2 JavaScript, Math, Property, Reference
The Math.LN2 property represents the natural logarithm of 2, approximately 0.693:
453 Math.LOG10E JavaScript, Math, Property, Reference
The Math.LOG10E property represents the base 10 logarithm of e, approximately 0.434:
454 Math.LOG2E JavaScript, Math, Property, Reference
The Math.LOG2E property represents the base 2 logarithm of e, approximately 1.442:
455 Math.PI JavaScript, Math, Property, Reference
The Math.PI property represents the ratio of the circumference of a circle to its diameter, approximately 3.14159:
456 Math.SQRT1_2 JavaScript, Math, Property, Reference
The Math.SQRT1_2 property represents the square root of 1/2 which is approximately 0.707:
457 Math.SQRT2 JavaScript, Math, Property, Reference
The Math.SQRT2 property represents the square root of 2, approximately 1.414:
458 Math.abs() JavaScript, Math, Method, Reference
The Math.abs() function returns the absolute value of a number
459 Math.acos() JavaScript, Math, Method, Reference
The Math.acos() function returns the arccosine (in radians) of a number, that is
460 Math.acosh() JavaScript, Math, Method, Reference
The Math.acosh() function returns the hyperbolic arc-cosine of a number, that is
461 Math.asin() JavaScript, Math, Method, Reference
The Math.asin() function returns the arcsine (in radians) of a number, that is
462 Math.asinh() JavaScript, Math, Method, Reference
The Math.asinh() function returns the hyperbolic arcsine of a number, that is
463 Math.atan() JavaScript, Math, Method, Reference
The Math.atan() function returns the arctangent (in radians) of a number, that is
464 Math.atan2() JavaScript, Math, Method, Reference
The Math.atan2() function returns the angle in the plane (in radians) between the positive x-axis and the ray from (0,0) to the point (x,y), for Math.atan2(y,x).
465 Math.atanh() JavaScript, Math, Method, Reference
The Math.atanh() function returns the hyperbolic arctangent of a number, that is
466 Math.cbrt() JavaScript, Math, Method, Reference
The Math.cbrt() function returns the cube root of a number, that is
467 Math.ceil() JavaScript, Math, Method, Reference
The Math.ceil() function always rounds a number up to the next largest whole number or integer.
468 Math.clz32() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.clz32() function returns the number of leading zero bits in the 32-bit binary representation of a number.
469 Math.cos() Geometry, JavaScript, Math, Method, Reference, Trigonometry, cos, cosine
The Math.cos() static function returns the cosine of the specified angle, which must be specified in radians. This value is
470 Math.cosh() JavaScript, Math, Method, Reference
The Math.cosh() function returns the hyperbolic cosine of a number, that can be expressed using the constant e:
471 Math.exp() JavaScript, Math, Method, Reference
The Math.exp() function returns ex, where x is the argument, and e is Euler's number (also known as Napier's constant), the base of the natural logarithms.
472 Math.expm1() JavaScript, Math, Method, Reference
The Math.expm1() function returns ex - 1, where x is the argument, and e the base of the natural logarithms.
473 Math.floor() JavaScript, Math, Method, Reference
The Math.floor() function returns the largest integer less than or equal to a given number.
474 Math.fround() JavaScript, Math, Method, Reference, fround
The Math.fround() function returns the nearest 32-bit single precision float representation of a Number.
475 Math.hypot() JavaScript, Math, Method, Reference
The Math.hypot() function returns the square root of the sum of squares of its arguments, that is:
476 Math.imul() JavaScript, Math, Method, Reference, imul
The Math.imul() function returns the result of the C-like 32-bit multiplication of the two parameters.
477 Math.log() JavaScript, Math, Method, Reference
The Math.log() function returns the natural logarithm (base e) of a number, that is
478 Math.log10() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.log10() function returns the base 10 logarithm of a number, that is
479 Math.log1p() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.log1p() function returns the natural logarithm (base e) of 1 + a number, that is
480 Math.log2() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.log2() function returns the base 2 logarithm of a number, that is
481 Math.max() JavaScript, Math, Method, Reference
The Math.max() function returns the largest of zero or more numbers.
482 Math.min() JavaScript, Lowest Number, Lowest Value, Math, Method, Minimum, Reference, Smallest, Smallest Number, Smallest Value, min
The static function Math.min() returns the lowest-valued number passed into it, or NaN if any parameter isn't a number and can't be converted into one.
483 Math.pow() JavaScript, Math, Method, Reference
The Math.pow() function returns the base to the exponent power, that is, baseexponent.
484 Math.random() JavaScript, Math, Method, Reference
The Math.random() function returns a floating-point, pseudo-random number in the range 0–1 (inclusive of 0, but not 1) with approximately uniform distribution over that range — which you can then scale to your desired range. The implementation selects the initial seed to the random number generation algorithm; it cannot be chosen or reset by the user.
485 Math.round() JavaScript, Math, Method, Number, Reference
The Math.round() function returns the value of a number rounded to the nearest integer.
486 Math.sign() JavaScript, Math, Method, Reference
The Math.sign() function returns either a positive or negative +/- 1, indicating the sign of a number passed into the argument. If the number passed into Math.sign() is 0, it will return a +/- 0. Note that if the number is positive, an explicit (+) will not be returned.
487 Math.sin() JavaScript, Math, Method, Reference
The Math.sin() function returns the sine of a number.
488 Math.sinh() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.sinh() function returns the hyperbolic sine of a number, that can be expressed using the constant e:
489 Math.sqrt() JavaScript, Math, Method, Reference
The Math.sqrt() function returns the square root of a number, that is
490 Math.tan() JavaScript, Math, Method, Reference
The Math.tan() function returns the tangent of a number.
491 Math.tanh() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.tanh() function returns the hyperbolic tangent of a number, that is
492 Math.trunc() ECMAScript 2015, JavaScript, Math, Method, Reference
The Math.trunc() function returns the integer part of a number by removing any fractional digits.
493 NaN JavaScript, Property, Reference
The global NaN property is a value representing Not-A-Number.
494 Number JavaScript, Number, Reference
The Number JavaScript object is a wrapper object allowing you to work with numerical values. A Number object is created using the Number() constructor. A primitive type object number is created using the Number() function.
495 Number.EPSILON ECMAScript 2015, JavaScript, Number, Property
The Number.EPSILON property represents the difference between 1 and the smallest floating point number greater than 1.
496 Number.MAX_SAFE_INTEGER ECMAScript 2015, JavaScript, Number, Property
The Number.MAX_SAFE_INTEGER constant represents the maximum safe integer in JavaScript (253 - 1).
497 Number.MAX_VALUE JavaScript, Number, Property, Reference
The Number.MAX_VALUE property represents the maximum numeric value representable in JavaScript.
498 Number.MIN_SAFE_INTEGER ECMAScript 2015, JavaScript, Number, Property
The Number.MIN_SAFE_INTEGER constant represents the minimum safe integer in JavaScript (-(253 - 1)).
499 Number.MIN_VALUE JavaScript, Number, Property
The Number.MIN_VALUE property represents the smallest positive numeric value representable in JavaScript.
500 Number.NEGATIVE_INFINITY JavaScript, Number, Property, Reference
The Number.NEGATIVE_INFINITY property represents the negative Infinity value.
501 Number.NaN JavaScript, Number, Property
The Number.NaN property represents Not-A-Number. Equivalent of NaN.
502 Number.POSITIVE_INFINITY JavaScript, Number, Property, Reference
The Number.POSITIVE_INFINITY property represents the positive Infinity value.
503 Number.isFinite() JavaScript, Method, Number, Reference
The Number.isFinite() method determines whether the passed value is a finite number.
504 Number.isInteger() JavaScript, Method, Number, Reference
The Number.isInteger() method determines whether the passed value is an integer.
505 Number.isNaN() ECMAScript 2015, JavaScript, Method, Number, isNaN
The Number.isNaN() method determines whether the passed value is NaN and its type is Number. It is a more robust version of the original, global isNaN().
506 Number.isSafeInteger() ECMAScript 2015, JavaScript, Method, Number
The Number.isSafeInteger() method determines whether the provided value is a number that is a safe integer.
507 Number.parseFloat() ECMAScript 2015, JavaScript, Method, Number
The Number.parseFloat() method parses a string argument and returns a floating point number.
508 Number.parseInt() ECMAScript 2015, JavaScript, Method, Number
The Number.parseInt() method parses a string argument and returns an integer of the specified radix or base.
509 Number.prototype JavaScript, Number, Property, Prototype
The Number.prototype property represents the prototype for the Number constructor.
510 Number.prototype.toExponential() JavaScript, Method, Number, Prototype
The toExponential() method returns a string representing the Number object in exponential notation.
511 Number.prototype.toFixed() JavaScript, Method, Number, Prototype, Reference
The toFixed() method formats a number using fixed-point notation.
512 Number.prototype.toLocaleString() Internationalization, JavaScript, Method, Number, Prototype
The toLocaleString() method returns a string with a language-sensitive representation of this number.
513 Number.prototype.toPrecision() JavaScript, Method, Number, Prototype
The toPrecision() method returns a string representing the Number object to the specified precision.
514 Number.prototype.toSource() JavaScript, Method, Non-standard, Number, Prototype
The toSource() method returns a string representing the source code of the object.
515 Number.prototype.toString() JavaScript, Method, Number, Prototype
The toString() method returns a string representing the specified Number object.
516 Number.prototype.valueOf() JavaScript, Method, Number, Prototype, Reference
The valueOf() method returns the wrapped primitive value of a Number object.
517 Number.toInteger() JavaScript, Method, Number, Obsolete
The Number.toInteger() method used to evaluate the passed value and convert it to an integer, but its implementation has been removed.
518 Object Constructor, JavaScript, Object
The Object constructor creates an object wrapper.
519 Object.assign() ECMAScript 2015, JavaScript, Method, Object, Reference, polyfill
The Object.assign() method copies all enumerable own properties from one or more source objects to a target object. It returns the target object.
520 Object.create() ECMAScript 5, JavaScript, Method, Null, Object, Reference, polyfill
The Object.create() method creates a new object, using an existing object as the prototype of the newly created object.
521 Object.defineProperties() ECMAScript 5, JavaScript, Method, Object
The Object.defineProperties() method defines new or modifies existing properties directly on an object, returning the object.
522 Object.defineProperty() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The static method Object.defineProperty() defines a new property directly on an object, or modifies an existing property on an object, and returns the object.
523 Additional examples for Object.defineProperty Examples, JavaScript, Object
This page provides additional examples for Object.defineProperty().
524 Object.entries() JavaScript, Method, Object, Reference
The Object.entries() method returns an array of a given object's own enumerable string-keyed property [key, value] pairs, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well). The order of the array returned by Object.entries() does not depend on how an object is defined. If there is a need for certain ordering then the array should be sorted first like Object.entries(obj).sort((a, b) => b[0].localeCompare(a[0]));.
525 Object.freeze() Change, Changeability, ECMAScript 5, JavaScript, Method, Mutability, Mutable, Object, Reference, freeze, lock
The Object.freeze() method freezes an object. A frozen object can no longer be changed; freezing an object prevents new properties from being added to it, existing properties from being removed, prevents changing the enumerability, configurability, or writability of existing properties, and prevents the values of existing properties from being changed. In addition, freezing an object also prevents its prototype from being changed. freeze() returns the same object that was passed in.
526 Object.fromEntries() JavaScript, Method, Object, Reference
The Object.fromEntries() method transforms a list of key-value pairs into an object.
527 Object.getNotifier() JavaScript, Method, Object, Obsolete
The Object.getNotifer() method was used to create an object that allows to synthetically trigger a change, but has been deprecated and removed in browsers.
528 Object.getOwnPropertyDescriptor() ECMAScript 5, JavaScript, Method, Object
The Object.getOwnPropertyDescriptor() method returns a property descriptor for an own property (that is, one directly present on an object and not in the object's prototype chain) of a given object.
529 Object.getOwnPropertyDescriptors() JavaScript, Method, Object
The Object.getOwnPropertyDescriptors() method returns all own property descriptors of a given object.
530 Object.getOwnPropertyNames() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object, Reference
The Object.getOwnPropertyNames() method returns an array of all properties (including non-enumerable properties except for those which use Symbol) found directly in a given object.
531 Object.getOwnPropertySymbols() ECMAScript 2015, JavaScript, Method, Object
The Object.getOwnPropertySymbols() method returns an array of all symbol properties found directly upon a given object.
532 Object.getPrototypeOf() ECMAScript 5, JavaScript, Method, Object
The Object.getPrototypeOf() method returns the prototype (i.e. the value of the internal [[Prototype]] property) of the specified object.
533 Object.is() Comparison, Condition, Conditional, ECMAScript 2015, Equality, JavaScript, Method, Object
The Object.is() method determines whether two values are the same value.
534 Object.isExtensible() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The Object.isExtensible() method determines if an object is extensible (whether it can have new properties added to it).
535 Object.isFrozen() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The Object.isFrozen() determines if an object is frozen.
536 Object.isSealed() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The Object.isSealed() method determines if an object is sealed.
537 Object.keys() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The Object.keys() method returns an array of a given object's own enumerable property names, in the same order as we get with a normal loop.
538 Object.observe() JavaScript, Method, Object, Obsolete
The Object.observe() method was used for asynchronously observing the changes to an object. It provided a stream of changes in the order in which they occur. However, this API has been deprecated and removed from browsers. You can use the more general Proxy object instead.
539 Object.preventExtensions() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object
The Object.preventExtensions() method prevents new properties from ever being added to an object (i.e. prevents future extensions to the object).
540 Object.prototype JavaScript, Object, Property
The Object.prototype is a property of the Object constructor. It is also the end of a prototype chain.
541 Object.prototype.__count__ JavaScript, Non-standard, Object, Obsolete, Property, Prototype
The __count__ property used to store the count of enumerable properties on the object, but it has been removed.
542 Object.prototype.__defineGetter__() Deprecated, JavaScript, Method, Object, Prototype
The __defineGetter__ method binds an object's property to a function to be called when that property is looked up.
543 Object.prototype.__defineSetter__() Deprecated, JavaScript, Method, Object, Prototype
The __defineSetter__ method binds an object's property to a function to be called when an attempt is made to set that property.
544 Object.prototype.__lookupGetter__() Deprecated, JavaScript, Method, Object, Prototype
The __lookupGetter__ method returns the function bound as a getter to the specified property.
545 Object.prototype.__lookupSetter__() Deprecated, JavaScript, Method, Object, Prototype
The __lookupSetter__ method returns the function bound as a setter to the specified property.
546 Object.prototype.__noSuchMethod__ JavaScript, Non-standard, Object, Obsolete, Property, Prototype
The __noSuchMethod__ property used to reference a function to be executed when a non-existent method is called on an object, but this function is no longer available.
547 Object.prototype.__parent__ JavaScript, Non-standard, Object, Obsolete, Property, Prototype
The __parent__ property used to point to an object's context, but it has been removed.
548 Object.prototype.__proto__ Deprecated, ECMAScript 2015, JavaScript, Object, Property, Prototype, Reference
The __proto__ property of Object.prototype is an accessor property (a getter function and a setter function) that exposes the internal [[Prototype]] (either an object or null) of the object through which it is accessed.
549 Object.prototype.constructor JavaScript, Object, Property, Prototype
The constructor property returns a reference to the Object constructor function that created the instance object. Note that the value of this property is a reference to the function itself, not a string containing the function's name.
550 Object.prototype.eval() JavaScript, Method, Object, Obsolete
The Object.eval() method used to evaluate a string of JavaScript code in the context of an object, however, this method has been removed.
551 Object.prototype.hasOwnProperty() JavaScript, Method, Object, Prototype, hasOwnProperty
The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property (as opposed to inheriting it).
552 Object.prototype.isPrototypeOf() JavaScript, Method, Object, Prototype, Reference, isPrototype
The isPrototypeOf() method checks if an object exists in another object's prototype chain.
553 Object.prototype.propertyIsEnumerable() JavaScript, Method, Object, Prototype
The propertyIsEnumerable() method returns a Boolean indicating whether the specified property is enumerable and is the object's own property.
554 Object.prototype.toLocaleString() JavaScript, Method, Object, Prototype, Reference
The toLocaleString() method returns a string representing the object. This method is meant to be overridden by derived objects for locale-specific purposes.
555 Object.prototype.toSource() JavaScript, Method, Non-standard, Object, Prototype
The toSource() method returns a string representing the source code of the object.
556 Object.prototype.toString() JavaScript, Method, Object, Prototype
The toString() method returns a string representing the object.
557 Object.prototype.unwatch() Debugging, Deprecated, JavaScript, Method, Object, Obsolete, Prototype, Reference
The unwatch() method removes a watchpoint set with the watch() method.
558 Object.prototype.valueOf() JavaScript, Method, Object, Prototype
The valueOf() method returns the primitive value of the specified object.
559 Object.prototype.watch() Debugging, Deprecated, JavaScript, Method, Object, Obsolete, Prototype
The watch() method watches for a property to be assigned a value and runs a function when that occurs.
560 Object.seal() ECMAScript 5, JavaScript, JavaScript 1.8.5, Method, Object, Reference
The Object.seal() method seals an object, preventing new properties from being added to it and marking all existing properties as non-configurable. Values of present properties can still be changed as long as they are writable.
561 Object.setPrototypeOf() ECMAScript 2015, JavaScript, Method, Object, Prototype
The Object.setPrototypeOf() method sets the prototype (i.e., the internal [[Prototype]] property) of a specified object to another object or null.
562 Object.unobserve() JavaScript, Method, Object, Obsolete
The Object.unobserve() method was used to remove observers set by Object.observe(), but has been deprecated and removed from Browsers. You can use the more general Proxy object instead.
563 Object.values() JavaScript, Method, Object, Reference
The Object.values() method returns an array of a given object's own enumerable property values, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).
564 Promise ECMAScript 2015, JavaScript, Promise, Reference
The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.
565 Promise.all() ECMAScript 2015, JavaScript, Method, Promise
The Promise.all() method returns a single Promise that fulfills when all of the promises passed as an iterable have been fulfilled or when the iterable contains no promises. It rejects with the reason of the first promise that rejects.
566 Promise.allSettled() JavaScript, Method, Promise, Reference, allSettled, asynchronous
The Promise.allSettled() method returns a promise that resolves after all of the given promises have either resolved or rejected, with an array of objects that each describes the outcome of each promise.
567 Promise.any() Experimental, JavaScript, Method, Promise, Reference
Promise.any() takes an iterable of Promise objects and, as soon as one of the promises in the iterable fulfills, returns a single promise that resolves with the value from that promise. If no promises in the iterable fulfill (if all of the given promises are rejected), then the returned promise is rejected with an object that is still up for debate: either an array of rejection reasons, or an AggregateError, a new subclass of Error that groups together individual errors. Essentially, this method is the opposite of Promise.all().
568 Promise.prototype JavaScript, Promise, Property, Reference
The Promise.prototype property represents the prototype for the Promise constructor.
569 Promise.prototype.catch() ECMAScript 2015, JavaScript, Method, Promise, Prototype
The catch() method returns a Promise and deals with rejected cases only. It behaves the same as calling Promise.prototype.then(undefined, onRejected) (in fact, calling obj.catch(onRejected) internally calls obj.then(undefined, onRejected)). This means that you have to provide an onRejected function even if you want to fall back to an undefined result value - for example obj.catch(() => {}).
570 Promise.prototype.finally() JavaScript, Method, Promises, Prototype, Reference, finally
The finally() method returns a Promise. When the promise is settled, i.e either fulfilled or rejected, the specified callback function is executed. This provides a way for code to be run whether the promise was fulfilled successfully or rejected once the Promise has been dealt with.
571 Promise.prototype.then() ECMAScript 2015, JavaScript, Method, Promise, Prototype
The then() method returns a Promise. It takes up to two arguments: callback functions for the success and failure cases of the Promise.
572 Promise.race() ECMAScript 2015, JavaScript, Method, Promise, Reference
The Promise.race() method returns a promise that fulfills or rejects as soon as one of the promises in an iterable fulfills or rejects, with the value or reason from that promise.
573 Promise.reject() ECMAScript 2015, JavaScript, Method, Promise, Reference
The Promise.reject() method returns a Promise object that is rejected with a given reason.
574 Promise.resolve() ECMAScript 2015, JavaScript, Method, Promise, Reference
The Promise.resolve() method returns a Promise object that is resolved with a given value. If the value is a promise, that promise is returned; if the value is a thenable (i.e. has a "then" method), the returned promise will "follow" that thenable, adopting its eventual state; otherwise the returned promise will be fulfilled with the value. This function flattens nested layers of promise-like objects (e.g. a promise that resolves to a promise that resolves to something) into a single layer.
575 Proxy ECMAScript 2015, JavaScript, Proxy
The Proxy object is used to define custom behavior for fundamental operations (e.g. property lookup, assignment, enumeration, function invocation, etc).
576 Proxy handler ECMAScript 2015, JavaScript, Proxy
The proxy's handler object is a placeholder object which contains traps for proxies.
577 handler.apply() ECMAScript 2015, JavaScript, Method, Proxy
The handler.apply() method is a trap for a function call.
578 handler.construct() ECMAScript 2015, JavaScript, Method, Proxy
The handler.construct() method is a trap for the new operator. In order for the new operation to be valid on the resulting Proxy object, the target used to initialize the proxy must itself have a [[Construct]] internal method (i.e. new target must be valid).
579 handler.defineProperty() ECMAScript 2015, JavaScript, Method, Proxy
The handler.defineProperty() method is a trap for Object.defineProperty().
580 handler.deleteProperty() ECMAScript 2015, JavaScript, Method, Proxy
The handler.deleteProperty() method is a trap for the delete operator.
581 handler.enumerate() ECMAScript 2015, JavaScript, Method, Obsolete, Proxy
The handler.enumerate() method used to be a trap for for...in statements, but has been removed from the ECMAScript standard in ES2016 and is deprecated in browsers.
582 handler.get() ECMAScript 2015, JavaScript, Method, Proxy
The handler.get() method is a trap for getting a property value.
583 handler.getOwnPropertyDescriptor() ECMAScript 2015, JavaScript, Method, Proxy
The handler.getOwnPropertyDescriptor() method is a trap for Object.getOwnPropertyDescriptor().
584 handler.getPrototypeOf() ECMAScript 2015, JavaScript, Method, Proxy
The handler.getPrototypeOf() method is a trap for the [[GetPrototypeOf]] internal method.
585 handler.has() ECMAScript 2015, JavaScript, Method, Proxy
The handler.has() method is a trap for the in operator.
586 handler.isExtensible() ECMAScript 2015, JavaScript, Method, Proxy
The handler.isExtensible() method is a trap for Object.isExtensible().
587 handler.ownKeys() ECMAScript 2015, JavaScript, Method, Proxy
The handler.ownKeys() method is a trap for Reflect.ownKeys().
588 handler.preventExtensions() ECMAScript 2015, JavaScript, Method, Proxy
The handler.preventExtensions() method is a trap for Object.preventExtensions().
589 handler.set() ECMAScript 2015, JavaScript, Method, Proxy
The handler.set() method is a trap for setting a property value.
590 handler.setPrototypeOf() ECMAScript 2015, JavaScript, Method, Prototype, Proxy
The handler.setPrototypeOf() method is a trap for Object.setPrototypeOf().
591 Proxy.revocable() ECMAScript 2015, JavaScript, Method, Proxy
The Proxy.revocable() method is used to create a revocable Proxy object.
592 RangeError Error, JavaScript, Object, RangeError
The RangeError object indicates an error when a value is not in the set or range of allowed values.
593 RangeError.prototype Error, JavaScript, Property, Prototype, RangeError
The RangeError.prototype property represents the prototype the RangeError constructor.
594 ReferenceError Error, JavaScript, Object, Reference, ReferenceError
The ReferenceError object represents an error when a non-existent variable is referenced.
595 ReferenceError.prototype Error, JavaScript, Property, Prototype, ReferenceError
The ReferenceError.prototype property represents the prototype for the ReferenceError constructor.
596 Reflect ECMAScript 2015, JavaScript, Overview, Reflect
Reflect is a built-in object that provides methods for interceptable JavaScript operations. The methods are the same as those of proxy handlers. Reflect is not a function object, so it's not constructible.
597 Comparing Reflect and Object methods JavaScript, JavaScript Object Model, Object, Overview, Reflect
The Reflect object, introduced in ES2015, is a built-in object that provides methods to interface with JavaScript objects. Some of the static functions that exist on Reflect also correspond to methods available on Object, which predates ES2015. Although some of the methods appear to be similar in their behavior, there are often subtle differences between them.
598 Reflect.apply() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.apply() method calls a target function with arguments as specified.
599 Reflect.construct() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.construct() method acts like the new operator, but as a function. It is equivalent to calling new target(...args). It gives also the added option to specify a different prototype.
600 Reflect.defineProperty() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.defineProperty() method is like Object.defineProperty() but returns a Boolean.
601 Reflect.deleteProperty() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.deleteProperty() method allows to delete properties. It is like the delete operator as a function.
602 Reflect.enumerate() ECMAScript 2015, JavaScript, Method, Obsolete, Reflect
The static Reflect.enumerate() method used to return an iterator with the enumerable own and inherited properties of the target object, but has been removed in ECMAScript 2016 and is deprecated in browsers.
603 Reflect.get() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.get() method works like getting a property from an object (target[propertyKey]) as a function.
604 Reflect.getOwnPropertyDescriptor() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.getOwnPropertyDescriptor() method is similar to Object.getOwnPropertyDescriptor(). It returns a property descriptor of the given property if it exists on the object, undefined otherwise.
605 Reflect.getPrototypeOf() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.getPrototypeOf() method is almost the same method as Object.getPrototypeOf(). It returns the prototype (i.e. the value of the internal [[Prototype]] property) of the specified object.
606 Reflect.has() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.has() method works like the in operator as a function.
607 Reflect.isExtensible() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.isExtensible() method determines if an object is extensible (whether it can have new properties added to it). It is similar to Object.isExtensible(), but with some differences.
608 Reflect.ownKeys() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.ownKeys() method returns an array of the target object's own property keys.
609 Reflect.preventExtensions() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.preventExtensions() method prevents new properties from ever being added to an object (i.e., prevents future extensions to the object).
610 Reflect.set() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.set() method works like setting a property on an object.
611 Reflect.setPrototypeOf() ECMAScript 2015, JavaScript, Method, Reference, Reflect
The static Reflect.setPrototypeOf() method is the same method as Object.setPrototypeOf(), except for its return type. It sets the prototype (i.e., the internal [[Prototype]] property) of a specified object to another object or to null, and returns true if the operation was successful, or false otherwise.
612 RegExp Constructor, JavaScript, Reference, RegExp, Regular Expressions
The RegExp constructor creates a regular expression object for matching text with a pattern.
613 RegExp.$1-$9 JavaScript, Non-standard, Property, Read-only, Reference, RegExp, Regular Expressions
The non-standard $1, $2, $3, $4, $5, $6, $7, $8, $9 properties are static and read-only properties of regular expressions that contain parenthesized substring matches.
614 RegExp.input ($_) JavaScript, Non-standard, Property, Reference, RegExp, Regular Expressions
The non-standard input property is a static property of regular expressions that contains the string against which a regular expression is matched. RegExp.$_ is an alias for this property.
615 RegExp.lastMatch ($&) JavaScript, Non-standard, Property, Read-only, Reference, RegExp, Regular Expressions
The non-standard lastMatch property is a static and read-only property of regular expressions that contains the last matched characters. RegExp.$& is an alias for this property.
616 RegExp.lastParen ($+) JavaScript, Non-standard, Property, Read-only, Reference, RegExp, Regular Expressions
The non-standard lastParen property is a static and read-only property of regular expressions that contains the last parenthesized substring match, if any. RegExp.$+ is an alias for this property.
617 RegExp.leftContext ($`) JavaScript, Non-standard, Property, Read-only, Reference, RegExp, Regular Expressions
The non-standard leftContext property is a static and read-only property of regular expressions that contains the substring preceding the most recent match. RegExp.$` is an alias for this property.
618 RegExp.prototype JavaScript, Property, Prototype, Reference, RegExp
The RegExp.prototype property represents the prototype object for the RegExp constructor.
619 RegExp.prototype.compile() Deprecated, JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The deprecated compile() method is used to (re-)compile a regular expression during execution of a script. It is basically the same as the RegExp constructor.
620 RegExp.prototype.dotAll Draft, JavaScript, NeedsLiveSample, Property, Prototype, Reference, RegExp, Regular Expressions
The dotAll property indicates whether or not the "s" flag is used with the regular expression. dotAll is a read-only property of an individual regular expression instance.
621 RegExp.prototype.exec() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The exec() method executes a search for a match in a specified string. Returns a result array, or null.
622 RegExp.prototype.flags ECMAScript 2015, JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The flags property returns a string consisting of the flags of the current regular expression object.
623 RegExp.prototype.global JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The global property indicates whether or not the "g" flag is used with the regular expression. global is a read-only property of an individual regular expression instance.
624 RegExp.prototype.ignoreCase JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The ignoreCase property indicates whether or not the "i" flag is used with the regular expression. ignoreCase is a read-only property of an individual regular expression instance.
625 RegExp.prototype.multiline JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The multiline property indicates whether or not the "m" flag is used with the regular expression. multiline is a read-only property of an individual regular expression instance.
626 RegExp.prototype.source JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The source property returns a String containing the source text of the regexp object, and it doesn't contain the two forward slashes on both sides and any flags.
627 RegExp.prototype.sticky ECMAScript 2015, JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The sticky property reflects whether or not the search is sticky (searches in strings only from the index indicated by the lastIndex property of this regular expression). sticky is a read-only property of an individual regular expression object.
628 RegExp.prototype.test() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The test() method executes a search for a match between a regular expression and a specified string. Returns true or false.
629 RegExp.prototype.toSource() JavaScript, Method, Non-standard, Prototype, Reference, RegExp, Regular Expressions
The toSource() method returns a string representing the source code of the object.
630 RegExp.prototype.toString() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The toString() method returns a string representing the regular expression.
631 RegExp.prototype.unicode ECMAScript 2015, JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The unicode property indicates whether or not the "u" flag is used with a regular expression. unicode is a read-only property of an individual regular expression instance.
632 RegExp.prototype[@@matchAll]() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The [@@matchAll] method returns all matches of the regular expression against a string.
633 RegExp.prototype[@@match]() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The [@@match]() method retrieves the matches when matching a string against a regular expression.
634 RegExp.prototype[@@replace]() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The [@@replace]() method replaces some or all matches of a this pattern in a string by a replacement, and returns the result of the replacement as a new string. The replacement can be a string or a function to be called for each match.
635 RegExp.prototype[@@search]() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The [@@search]() method executes a search for a match between a this regular expression and a string.
636 RegExp.prototype[@@split]() JavaScript, Method, Prototype, Reference, RegExp, Regular Expressions
The [@@split]() method splits a String object into an array of strings by separating the string into substrings.
637 RegExp.rightContext ($') JavaScript, Non-standard, Property, Read-only, Reference, RegExp, Regular Expressions
The non-standard rightContext property is a static and read-only property of regular expressions that contains the substring following the most recent match. RegExp.$' is an alias for this property.
638 get RegExp[@@species] JavaScript, Property, Prototype, Reference, RegExp, Regular Expressions
The RegExp[@@species] accessor property returns the RegExp constructor.
639 regexp.lastIndex JavaScript, Property, Reference, RegExp, Regular Expressions
The lastIndex is a read/write integer property of regular expression instances that specifies the index at which to start the next match.
640 Set ECMAScript 2015, Global Objects, JavaScript, Object, Reference, set
The Set object lets you store unique values of any type, whether primitive values or object references.
641 Set.prototype ECMAScript 2015, JavaScript, Property, set
The Set.prototype property represents the prototype for the Set constructor.
642 Set.prototype.add() ECMAScript 2015, JavaScript, Method, Prototype, Reference, set
The add() method appends a new element with a specified value to the end of a Set object.
643 Set.prototype.clear() ECMAScript 2015, JavaScript, Method, Prototype, Reference, set
The clear() method removes all elements from a Set object.
644 Set.prototype.delete() ECMAScript 2015, JavaScript, Method, Prototype, Reference, set
The delete() method removes the specified element from a Set object.
645 Set.prototype.entries() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, set
The entries() method returns a new Iterator object that contains an array of [value, value] for each element in the Set object, in insertion order. For Set objects there is no key like in Map objects. However, to keep the API similar to the Map object, each entry has the same value for its key and value here, so that an array [value, value] is returned.
646 Set.prototype.forEach() ECMAScript 2015, JavaScript, Method, Prototype, Reference, set
The forEach() method executes a provided function once for each value in the Set object, in insertion order.
647 Set.prototype.has() ECMAScript 2015, JavaScript, Method, Prototype, set
The has() method returns a boolean indicating whether an element with the specified value exists in a Set object or not.
648 Set.prototype.size ECMAScript 2015, JavaScript, Property, Prototype, set
The size accessor property returns the number of (unique) elements in a Set object.
649 Set.prototype.values() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, set
The values() method returns a new Iterator object that contains the values for each element in the Set object in insertion order.
650 Set.prototype[@@iterator]() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, Reference, set
The initial value of the @@iterator property is the same function object as the initial value of the values property.
651 get Set[@@species] ECMAScript 2015, JavaScript, Property, set
The Set[@@species] accessor property returns the Set constructor.
652 SharedArrayBuffer Constructor, JavaScript, Shared Memory, SharedArrayBuffer, TypedArrays
The SharedArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer, similar to the ArrayBuffer object, but in a way that they can be used to create views on shared memory. Unlike an ArrayBuffer, a SharedArrayBuffer cannot become detached.
653 Planned changes to shared memory Fetch, HTML, JavaScript, Security, SharedArrayBuffer, Spectre, postMessage
There is standardization work ongoing that enables developers to create SharedArrayBuffer objects again, but they will need to make some changes in order to be able to use these across threads (i.e., postMessage() throws by default). These changes enable further isolation between sites and help reduce the impact of attacks with high-resolution timers, which can be created with shared memory.
654 SharedArrayBuffer.prototype JavaScript, Property, Shared Memory, SharedArrayBuffer, TypedArrays
The SharedArrayBuffer.prototype property represents the prototype for the SharedArrayBuffer object.
655 SharedArrayBuffer.prototype.byteLength JavaScript, Property, Shared Memory, SharedArrayBuffer, TypedArrays
The byteLength accessor property represents the length of an SharedArrayBuffer in bytes.
656 SharedArrayBuffer.prototype.slice() JavaScript, Method, Prototype, Shared Memory, SharedArrayBuffer, TypedArrays
The SharedArrayBuffer.prototype.slice() method returns a new SharedArrayBuffer whose contents are a copy of this SharedArrayBuffer's bytes from begin, inclusive, up to end, exclusive. If either begin or end is negative, it refers to an index from the end of the array, as opposed to from the beginning. This method has the same algorithm as Array.prototype.slice().
657 String ECMAScript 2015, JavaScript, Reference, String
The String global object is a constructor for strings or a sequence of characters.
658 String length JavaScript, Property, Reference, String, String Length, length
The length property of a String object contains the length of the string, in UTF-16 code units. length is a read-only data property of string instances.
659 String.fromCharCode() JavaScript, Method, Reference, String, UTF-16, Unicode
The static String.fromCharCode() method returns a string created from the specified sequence of UTF-16 code units.
660 String.fromCodePoint() ECMAScript 2015, JavaScript, Method, Reference, String, UTF-32, Unicode
The static String.fromCodePoint() method returns a string created by using the specified sequence of code points.
661 String.prototype JavaScript, Property, Prototype, Reference, String
The String.prototype property represents the String prototype object.
662 String.prototype.anchor() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The anchor() method creates an <a> HTML anchor element that is used as a hypertext target.
663 String.prototype.big() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The big() method creates a <big> HTML element that causes a string to be displayed in a big font.
664 String.prototype.blink() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The blink() method creates a <blink> HTML element that causes a string to blink.
665 String.prototype.bold() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The bold() method creates a <b> HTML element that causes a string to be displayed as bold.
666 String.prototype.charAt() JavaScript, Method, Prototype, Reference, String
The String object's charAt() method returns a new string consisting of the single UTF-16 code unit located at the specified offset into the string.
667 String.prototype.charCodeAt() JavaScript, Method, Reference, String, Unicode
The charCodeAt() method returns an integer between 0 and 65535 representing the UTF-16 code unit at the given index.
668 String.prototype.codePointAt() ECMAScript 2015, JavaScript, Method, Prototype, Reference, String
The codePointAt() method returns a non-negative integer that is the Unicode code point value.
669 String.prototype.concat() JavaScript, Method, Prototype, Reference, String
The concat() method concatenates the string arguments to the calling string and returns a new string.
670 String.prototype.endsWith() JavaScript, Method, Prototype, Reference, String
The endsWith() method determines whether a string ends with the characters of a specified string, returning true or false as appropriate.
671 String.prototype.fixed() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The fixed() method creates a <tt> HTML element that causes a string to be displayed in fixed-pitch font.
672 String.prototype.fontcolor() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The fontcolor() method creates a <font> HTML element that causes a string to be displayed in the specified font color.
673 String.prototype.fontsize() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The fontsize() method creates a <font> HTML element that causes a string to be displayed in the specified font size.
674 String.prototype.includes() JavaScript, Method, Prototype, Reference, String
The includes() method determines whether one string may be found within another string, returning true or false as appropriate.
675 String.prototype.indexOf() JavaScript, Method, Prototype, Reference, String
The indexOf() method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.
676 String.prototype.italics() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, String
The italics() method creates an <i> HTML element that causes a string to be italic.
677 String.prototype.lastIndexOf() JavaScript, Method, Prototype, Reference, String, lastIndexOf
The lastIndexOf() method returns the index within the calling String object of the last occurrence of the specified value, searching backwards from fromIndex. Returns -1 if the value is not found.
678 String.prototype.link() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The link() method creates a string representing the code for an <a> HTML element to be used as a hypertext link to another URL.
679 String.prototype.localeCompare() Internationalization, JavaScript, Method, Prototype, Reference, String
The localeCompare() method returns a number indicating whether a reference string comes before or after or is the same as the given string in sort order.
680 String.prototype.match() JavaScript, Method, Prototype, Reference, Regular Expressions, String
The match() method retrieves the result of matching a string against a regular expression.
681 String.prototype.matchAll() JavaScript, Method, Prototype, Reference, Regular Expressions, String
The matchAll() method returns an iterator of all results matching a string against a regular expression, including capturing groups.
682 String.prototype.normalize() ECMAScript 2015, JavaScript, Method, Prototype, Reference, String, Unicode
The normalize() method returns the Unicode Normalization Form of a given string (if the value isn't a string, it will be converted to one first).
683 String.prototype.padEnd() JavaScript, Method, Prototype, Reference, String
The padEnd() method pads the current string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the end of the current string.
684 String.prototype.padStart() Advanced, Intermediate, JavaScript, Method, Prototype, Reference, String
The padStart() method pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length.
685 String.prototype.quote() JavaScript, Method, Obsolete, Prototype, Reference, String
The non-standard quote() method returns a copy of the string, replacing various special characters in the string with their escape sequences and wrapping the result in double-quotes (").
686 String.prototype.repeat() ECMAScript 2015, JavaScript, Method, Prototype, Reference, String
The repeat() method constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together.
687 String.prototype.replace() Expressions, JavaScript, Method, Prototype, Reference, Regular, String
The replace() method returns a new string with some or all matches of a pattern replaced by a replacement.
688 String.prototype.search() JavaScript, Method, Prototype, Reference, Regular Expressions, String
The search() method executes a search for a match between a regular expression and this String object.
689 String.prototype.slice() JavaScript, Method, Prototype, Reference, String
The slice() method extracts a section of a string and returns it as a new string, without modifying the original string.
690 String.prototype.small() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The small() method creates a <small> HTML element that causes a string to be displayed in a small font.
691 String.prototype.split() JavaScript, Method, Prototype, Reference, Regular Expressions, String
The split() method turns a String into an array of strings, by separating the string at each instance of a specified separator string.
692 String.prototype.startsWith() ECMAScript 2015, JavaScript, Method, Prototype, Reference, String
The startsWith() method determines whether a string begins with the characters of a specified string, returning true or false as appropriate.
693 String.prototype.strike() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, String
The strike() method creates a <strike> HTML element that causes a string to be displayed as struck-out text.
694 String.prototype.sub() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, String
The sub() method creates a <sub> HTML element that causes a string to be displayed as subscript.
695 String.prototype.substr() Deprecated, JavaScript, Method, Prototype, Reference, String
The substr() method returns a portion of the string, starting at the specified index and extending for a given number of characters afterward.
696 String.prototype.substring() JavaScript, Method, Prototype, Reference, String
The substring() method returns the part of the string between the start and end indexes, or to the end of the string.
697 String.prototype.sup() Deprecated, HTML wrapper methods, JavaScript, Method, Prototype, Reference, String
The sup() method creates a <sup> HTML element that causes a string to be displayed as superscript.
698 String.prototype.toLocaleLowerCase() Internationalization, JavaScript, Method, Prototype, Reference, String
The toLocaleLowerCase() method returns the calling string value converted to lower case, according to any locale-specific case mappings.
699 String.prototype.toLocaleUpperCase() Internationalization, JavaScript, Method, Prototype, Reference, String
The toLocaleUpperCase() method returns the calling string value converted to upper case, according to any locale-specific case mappings.
700 String.prototype.toLowerCase() JavaScript, Method, Prototype, Reference, String
The toLowerCase() method returns the calling string value converted to lower case.
701 String.prototype.toSource() JavaScript, Method, Non-standard, Prototype, Reference, String
The toSource() method returns a string representing the source code of the object.
702 String.prototype.toString() JavaScript, Method, Prototype, Reference, String
The toString() method returns a string representing the specified object.
703 String.prototype.toUpperCase() JavaScript, Method, Prototype, Reference, String
The toUpperCase() method returns the calling string value converted to uppercase (the value will be converted to a string if it isn't one).
704 String.prototype.trim() ECMAScript 5, JavaScript, Method, Prototype, Reference, String
The trim() method removes whitespace from both ends of a string. Whitespace in this context is all the whitespace characters (space, tab, no-break space, etc.) and all the line terminator characters (LF, CR, etc.).
705 String.prototype.trimEnd() JavaScript, Method, Prototype, Reference, String
The trimEnd() method removes whitespace from the end of a string. trimRight() is an alias of this method.
706 String.prototype.trimStart() JavaScript, Method, Prototype, Reference, String
The trimStart() method removes whitespace from the beginning of a string. trimLeft() is an alias of this method.
707 String.prototype.valueOf() JavaScript, Method, Prototype, Reference, String
The valueOf() method returns the primitive value of a String object.
708 String.prototype[@@iterator]() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, Reference, String
The [@@iterator]() method returns a new Iterator object that iterates over the code points of a String value, returning each code point as a String value.
709 String.raw() ECMAScript 2015, JavaScript, Method, Reference, String
The static String.raw() method is a tag function of template literals, similar to the r prefix in Python or the @ prefix in C# for string literals (yet there is a difference: see explanations in this issue). It's used to get the raw string form of template strings, that is, substitutions (e.g. ${foo}) are processed, but escapes (e.g. \n) are not.
710 Symbol ECMAScript 2015, JavaScript, Symbol
The data type symbol is a primitive data type. The Symbol() function returns a value of type symbol, has static properties that expose several members of built-in objects, has static methods that expose the global symbol registry, and resembles a built-in object class but is incomplete as a constructor because it does not support the syntax "new Symbol()".
711 Symbol.asyncIterator ECMAScript 2018, JavaScript, Property, Reference, Symbol, asynchronous
The Symbol.asyncIterator well-known symbol specifies the default AsyncIterator for an object. If this property is set on an object, it is an async iterable and can be used in a for await...of loop.
712 Symbol.for() ECMAScript 2015, JavaScript, Method, Symbol
The Symbol.for(key) method searches for existing symbols in a runtime-wide symbol registry with the given key and returns it if found. Otherwise a new symbol gets created in the global symbol registry with this key.
713 Symbol.hasInstance ECMAScript 2015, JavaScript, Property, Reference, Symbol
The Symbol.hasInstance well-known symbol is used to determine if a constructor object recognizes an object as its instance. The instanceof operator's behavior can be customized by this symbol.
714 Symbol.isConcatSpreadable ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.isConcatSpreadable well-known symbol is used to configure if an object should be flattened to its array elements when using the Array.prototype.concat() method.
715 Symbol.iterator ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.iterator well-known symbol specifies the default iterator for an object. Used by for...of.
716 Symbol.keyFor() ECMAScript 2015, JavaScript, Method, Symbol
The Symbol.keyFor(sym) method retrieves a shared symbol key from the global symbol registry for the given symbol.
717 Symbol.match ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.match well-known symbol specifies the matching of a regular expression against a string. This function is called by the String.prototype.match() method.
718 Symbol.matchAll JavaScript, Property, Reference, Symbol
The Symbol.matchAll well-known symbol returns an iterator, that yields matches of the regular expression against a string. This function is called by the String.prototype.matchAll() method.
719 Symbol.prototype JavaScript, Property, Symbol
The Symbol.prototype property represents the prototype for the Symbol constructor.
720 Symbol.prototype.description JavaScript, Property, Prototype, Symbol
The read-only description property is a string returning the optional description of Symbol objects.
721 Symbol.prototype.toSource() JavaScript, Method, Prototype, Symbol
The toSource() method returns a string representing the source code of the object.
722 Symbol.prototype.toString() ECMAScript 2015, JavaScript, Method, Prototype, Symbol
The toString() method returns a string representing the specified Symbol object.
723 Symbol.prototype.valueOf() ECMAScript 2015, JavaScript, Method, Prototype, Symbol
The valueOf() method returns the primitive value of a Symbol object.
724 Symbol.prototype[@@toPrimitive] ECMAScript 2015, JavaScript, Method, Prototype, Symbol
The [@@toPrimitive]() method converts a Symbol object to a primitive value.
725 Symbol.replace ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.replace well-known symbol specifies the method that replaces matched substrings of a string. This function is called by the String.prototype.replace() method.
726 Symbol.search ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.search well-known symbol specifies the method that returns the index within a string that matches the regular expression. This function is called by the String.prototype.search() method.
727 Symbol.species ECMAScript 2015, JavaScript, Property, Symbol
The well-known symbol Symbol.species specifies a function-valued property that the constructor function uses to create derived objects.
728 Symbol.split ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.split well-known symbol specifies the method that splits a string at the indices that match a regular expression. This function is called by the String.prototype.split() method.
729 Symbol.toPrimitive ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.toPrimitive is a symbol that specifies a function valued property that is called to convert an object to a corresponding primitive value.
730 Symbol.toStringTag ECMAScript 2015, JavaScript, Property, Reference, Symbol
The Symbol.toStringTag well-known symbol is a string valued property that is used in the creation of the default string description of an object. It is accessed internally by the Object.prototype.toString() method.
731 Symbol.unscopables ECMAScript 2015, JavaScript, Property, Symbol
The Symbol.unscopables well-known symbol is used to specify an object value of whose own and inherited property names are excluded from the with environment bindings of the associated object.
732 SyntaxError Error, JavaScript, Object, Reference, SyntaxError
The SyntaxError object represents an error when trying to interpret syntactically invalid code.
733 SyntaxError.prototype Error, JavaScript, Property, Prototype, SyntaxError
The SyntaxError.prototype property represents the prototype for the SyntaxError constructor.
734 TypeError Error, JavaScript, Object, Reference, TypeError
The TypeError object represents an error when an operation could not be performed, typically (but not exclusively) when a value is not of the expected type.
735 TypeError.prototype Error, JavaScript, Property, Prototype, TypeError
The TypeError.prototype property represents the prototype for the TypeError constructor.
736 TypedArray JavaScript, TypedArray, TypedArrays
A TypedArray object describes an array-like view of an underlying binary data buffer. There is no global property named TypedArray, nor is there a directly visible TypedArray constructor.  Instead, there are a number of different global properties, whose values are typed array constructors for specific element types, listed below. On the following pages you will find common properties and methods that can be used with any typed array containing elements of any type.
737 TypedArray.BYTES_PER_ELEMENT JavaScript, Property, TypedArray, TypedArrays
The TypedArray.BYTES_PER_ELEMENT property represents the size in bytes of each element in an typed array.
738 TypedArray.from() ECMAScript 2015, JavaScript, Method, TypedArray, TypedArrays, from
The TypedArray.from() method creates a new typed array from an array-like or iterable object. This method is nearly the same as Array.from().
739 TypedArray.name JavaScript, Property, TypedArray, TypedArrays
The TypedArray.name property represents a string value of the typed array constructor name.
740 TypedArray.of() ECMAScript 2015, JavaScript, Method, TypedArray, TypedArrays
The TypedArray.of() method creates a new typed array from a variable number of arguments. This method is nearly the same as Array.of().
741 TypedArray.prototype JavaScript, Property, TypedArray, TypedArrays
The TypedArray.prototype property represents the prototype for TypedArray constructors.
742 TypedArray.prototype.buffer JavaScript, Property, Prototype, TypedArray, TypedArrays
The buffer accessor property represents the ArrayBuffer referenced by a TypedArray at construction time.
743 TypedArray.prototype.byteLength JavaScript, Property, Prototype, TypedArray, TypedArrays
The byteLength accessor property represents the length (in bytes) of a typed array.
744 TypedArray.prototype.byteOffset JavaScript, Property, Prototype, TypedArray, TypedArrays
The byteOffset accessor property represents the offset (in bytes) of a typed array from the start of its ArrayBuffer.
745 TypedArray.prototype.copyWithin() JavaScript, Method, Prototype, TypedArray, TypedArrays
The copyWithin() method copies the sequence of array elements within the array to the position starting at target. The copy is taken from the index positions of the second and third arguments start and end. The end argument is optional and defaults to the length of the array. This method has the same algorithm as Array.prototype.copyWithin. TypedArray is one of the typed array types here.
746 TypedArray.prototype.entries() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The entries() method returns a new Array iterator object that contains the key/value pairs for each index in the array.
747 TypedArray.prototype.every() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The every() method tests whether all elements in the typed array pass the test implemented by the provided function. This method has the same algorithm as Array.prototype.every(). TypedArray is one of the typed array types here.
748 TypedArray.prototype.fill() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The fill() method fills all the elements of a typed array from a start index to an end index with a static value. This method has the same algorithm as Array.prototype.fill(). TypedArray is one of the typed array types here.
749 TypedArray.prototype.filter() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The filter() method creates a new typed array with all elements that pass the test implemented by the provided function. This method has the same algorithm as Array.prototype.filter(). TypedArray is one of the typed array types here.
750 TypedArray.prototype.find() ECMAScript 2015, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The find() method returns a value in the typed array, if an element satisfies the provided testing function. Otherwise undefined is returned. TypedArray is one of the typed array types here.
751 TypedArray.prototype.findIndex() ECMAScript 2015, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The findIndex() method returns an index in the typed array, if an element in the typed array satisfies the provided testing function. Otherwise -1 is returned.
752 TypedArray.prototype.forEach() ECMAScript 2015, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The forEach() method executes a provided function once per array element. This method has the same algorithm as Array.prototype.forEach(). TypedArray is one of the typed array types here.
753 TypedArray.prototype.includes() ECMAScript 2016, JavaScript, Method, Prototype, TypedArray, TypedArrays
The includes() method determines whether a typed array includes a certain element, returning true or false as appropriate. This method has the same algorithm as Array.prototype.includes(). TypedArray is one of the typed array types here.
754 TypedArray.prototype.indexOf() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The indexOf() method returns the first index at which a given element can be found in the typed array, or -1 if it is not present. This method has the same algorithm as Array.prototype.indexOf(). TypedArray is one of the typed array types here.
755 TypedArray.prototype.join() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The join() method joins all elements of an array into a string. This method has the same algorithm as Array.prototype.join(). TypedArray is one of the typed array types here.
756 TypedArray.prototype.keys() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The keys() method returns a new Array Iterator object that contains the keys for each index in the array.
757 TypedArray.prototype.lastIndexOf() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The lastIndexOf() method returns the last index at which a given element can be found in the typed array, or -1 if it is not present. The typed array is searched backwards, starting at fromIndex. This method has the same algorithm as Array.prototype.lastIndexOf(). TypedArray is one of the typed array types here.
758 TypedArray.prototype.length JavaScript, Property, Prototype, TypedArray, TypedArrays
The length accessor property represents the length (in elements) of a typed array.
759 TypedArray.prototype.map() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The map() method creates a new typed array with the results of calling a provided function on every element in this typed array. This method has the same algorithm as Array.prototype.map(). TypedArray is one of the typed array types here.
760 TypedArray.prototype.move() JavaScript, Method, Non-standard, Obsolete, Prototype, TypedArray
The move() method used to copy the sequence of array elements within the array to the position starting at target. However, this non-standard method has been replaced with the standard TypedArray.prototype.copyWithin() method. TypedArray is one of the typed array types here.
761 TypedArray.prototype.reduce() JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The reduce() method applies a function against an accumulator and each value of the typed array (from left-to-right) has to reduce it to a single value. This method has the same algorithm as Array.prototype.reduce(). TypedArray is one of the typed array types here.
762 TypedArray.prototype.reduceRight() JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The reduceRight() method applies a function against an accumulator and each value of the typed array (from right-to-left) has to reduce it to a single value. This method has the same algorithm as Array.prototype.reduceRight(). TypedArray is one of the typed array types here.
763 TypedArray.prototype.reverse() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The reverse() method reverses a typed array in place. The first typed array element becomes the last and the last becomes the first. This method has the same algorithm as Array.prototype.reverse(). TypedArray is one of the typed array types here.
764 TypedArray.prototype.set() JavaScript, Method, Prototype, Reference, TypedArray
The set() method stores multiple values in the typed array, reading input values from a specified array.
765 TypedArray.prototype.slice() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The slice() method returns a shallow copy of a portion of a typed array into a new typed array object. This method has the same algorithm as Array.prototype.slice(). TypedArray is one of the typed array types here.
766 TypedArray.prototype.some() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The some() method tests whether some element in the typed array passes the test implemented by the provided function. This method has the same algorithm as Array.prototype.some(). TypedArray is one of the typed array types here.
767 TypedArray.prototype.sort() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The sort() method sorts the elements of a typed array numerically in place and returns the typed array. This method has the same algorithm as Array.prototype.sort(), except that sorts the values numerically instead of as strings. TypedArray is one of the typed array types here.
768 TypedArray.prototype.subarray() JavaScript, Method, Prototype, TypedArray, TypedArrays
The subarray() method returns a new TypedArray on the same ArrayBuffer store and with the same element types as for this TypedArray object. The begin offset is inclusive and the end offset is exclusive. TypedArray is one of the typed array types.
769 TypedArray.prototype.toLocaleString() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray, TypedArrays
The toLocaleString() method returns a string representing the elements of the typed array. The elements are converted to strings and are separated by a locale-specific string (such as a comma “,”). This method has the same algorithm as Array.prototype.toLocaleString() and, as the typed array elements are numbers, the same algorithm as Number.prototype.toLocaleString() applies for each element. TypedArray is one of the typed array types here.
770 TypedArray.prototype.toString() ECMAScript 2015, JavaScript, Method, Prototype, TypedArray
The toString() method returns a string representing the specified array and its elements. This method has the same algorithm as Array.prototype.toString(). TypedArray is one of the typed array types here.
771 TypedArray.prototype.values() ECMAScript 2015, Iterator, JavaScript, Method, Prototype, TypedArray, TypedArrays
The values() method returns a new Array Iterator object that contains the values for each index in the array.
772 TypedArray.prototype[@@iterator]() Iterator, JavaScript, Method, Prototype, Reference, TypedArray, TypedArrays
The initial value of the @@iterator property is the same function object as the initial value of the values property.
773 get TypedArray[@@species] JavaScript, Property, Prototype, TypedArray, TypedArrays
The TypedArray[@@species] accessor property returns the constructor of a typed array.
774 URIError Error, JavaScript, Object, Reference, URIError
The URIError object represents an error when a global URI handling function was used in a wrong way.
775 URIError.prototype Error, JavaScript, Property, Prototype, URIError
The URIError.prototype property represents the prototype for the URIError constructor.
776 Uint16Array Constructor, JavaScript, TypedArray, TypedArrays, Uint16Array
The Uint16Array typed array represents an array of 16-bit unsigned integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
777 Uint32Array Constructor, JavaScript, TypedArray, TypedArrays
The Uint32Array typed array represents an array of 32-bit unsigned integers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
778 Uint8Array Constructor, JavaScript, TypedArray, TypedArrays, Uint8Array
The Uint8Array typed array represents an array of 8-bit unsigned integers. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
779 Uint8ClampedArray Constructor, JavaScript, TypedArray, TypedArrays, Uint8ClampedArray
The Uint8ClampedArray typed array represents an array of 8-bit unsigned integers clamped to 0-255; if you specified a value that is out of the range of [0,255], 0 or 255 will be set instead; if you specify a non-integer, the nearest integer will be set. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).
780 WeakMap ECMAScript 2015, JavaScript, Reference, WeakMap
The WeakMap object is a collection of key/value pairs in which the keys are weakly referenced. The keys must be objects and the values can be arbitrary values.
781 WeakMap.prototype ECMAScript 2015, JavaScript, Property, WeakMap
The WeakMap.prototype property represents the prototype for the WeakMap constructor.
782 WeakMap.prototype.clear() JavaScript, Method, Obsolete, Prototype, WeakMap
The clear() method used to remove all elements from a WeakMap object, but is no longer part of ECMAScript and its implementations.
783 WeakMap.prototype.delete() ECMAScript 2015, JavaScript, Method, Prototype, Reference, WeakMap
The delete() method removes the specified element from a WeakMap object.
784 WeakMap.prototype.get() ECMAScript 2015, JavaScript, Method, Prototype, WeakMap
The get() method returns a specified element from a WeakMap object.
785 WeakMap.prototype.has() ECMAScript 2015, JavaScript, Method, Prototype, WeakMap
The has() method returns a boolean indicating whether an element with the specified key exists in the WeakMap object or not.
786 WeakMap.prototype.set() ECMAScript 2015, JavaScript, Method, Prototype, WeakMap
The set() method adds a new element with a specified key and value to a WeakMap object.
787 WeakSet ECMAScript 2015, JavaScript, WeakSet
The WeakSet object lets you store weakly held objects in a collection.
788 WeakSet.prototype ECMAScript 2015, JavaScript, Property, WeakSet
The WeakSet.prototype property represents the prototype for the WeakSet constructor.
789 WeakSet.prototype.add() ECMAScript 2015, JavaScript, Method, Prototype, WeakSet
The add() method appends a new object to the end of a WeakSet object.
790 WeakSet.prototype.clear() JavaScript, Method, Obsolete, Prototype, WeakSet
The clear() method used to remove all elements from a WeakSet object, but is no longer part of ECMAScript and its implementations.
791 WeakSet.prototype.delete() ECMAScript 2015, JavaScript, Method, Prototype, WeakSet
The delete() method removes the specified element from a WeakSet object.
792 WeakSet.prototype.has() ECMAScript 2015, JavaScript, Method, Prototype, WeakSet
The has() method returns a boolean indicating whether an object exists in a WeakSet or not.
793 WebAssembly API, JavaScript, Object, Reference, WebAssembly
The WebAssembly JavaScript object acts as the namespace for all WebAssembly-related functionality.
794 WebAssembly.CompileError() API, CompileError, Constructor, Error, JavaScript, NativeError, Reference, WebAssembly
The WebAssembly.CompileError() constructor creates a new WebAssembly CompileError object, which indicates an error during WebAssembly decoding or validation.
795 WebAssembly.Global API, Constructor, JavaScript, Reference, WebAssembly, global
A WebAssembly.Global object represents a global variable instance, accessible from both JavaScript and importable/exportable across one or more WebAssembly.Module instances. This allows dynamic linking of multiple modules.
796 WebAssembly.Global.prototype JavaScript, Property, Prototype, WebAssembly, global
The WebAssembly.Global.prototype property represents the prototype for the WebAssembly.Global() constructor.
797 WebAssembly.Instance API, Constructor, JavaScript, Reference, WebAssembly, instance
A WebAssembly.Instance object is a stateful, executable instance of a WebAssembly.Module.  Instance objects contain all the Exported WebAssembly functions that allow calling into WebAssembly code from JavaScript.
798 WebAssembly.Instance.prototype JavaScript, Property, Prototype, WebAssembly, instance
The WebAssembly.Instance.prototype property represents the prototype for the WebAssembly.Instance() constructor.
799 WebAssembly.Instance.prototype.exports API, JavaScript, Property, Reference, WebAssembly, exports, instance
The exports readonly property of the WebAssembly.Instance object prototype returns an object containing as its members all the functions exported from the WebAssembly module instance, to allow them to be accessed and used by JavaScript.
800 WebAssembly.LinkError() API, Constructor, JavaScript, LinkError, Reference, WebAssembly
The WebAssembly.LinkError() constructor creates a new WebAssembly LinkError object, which indicates an error during module instantiation (besides traps from the start function).
801 WebAssembly.Memory() API, Constructor, JavaScript, Object, Reference, WebAssembly, memory
The WebAssembly.Memory() constructor creates a new Memory object whose buffer property is a resizable ArrayBuffer that holds the raw bytes of memory accessed by a WebAssembly Instance.
802 WebAssembly.Memory.prototype JavaScript, Property, Prototype, WebAssembly, memory
The WebAssembly.Memory.prototype property represents the prototype for the WebAssembly.Memory() constructor.
803 WebAssembly.Memory.prototype.buffer API, Buffer, JavaScript, Property, Reference, WebAssembly, memory
The buffer prototype property of the Memory object returns the buffer contained in the memory.
804 WebAssembly.Memory.prototype.grow() API, JavaScript, Method, Reference, WebAssembly, grow, memory
The grow() protoype method of the Memory object increases the size of the memory instance by a specified number of WebAssembly pages.
805 WebAssembly.Module API, Constructor, JavaScript, Module, Reference, WebAssembly
All Module instances inherit from the Module() constructor's prototype object — this can be modified to affect all Module instances.
806 WebAssembly.Module.customSections() API, Constructor, JavaScript, Method, Module, Object, Reference, WebAssembly, customSections
The WebAssembly.customSections() function returns a copy of the contents of all custom sections in the given module with the given string name.
807 WebAssembly.Module.exports() API, Constructor, JavaScript, Method, Module, Object, Reference, WebAssembly, exports
The WebAssembly.Module.exports() function returns an array containing descriptions of all the declared exports of the given Module.
808 WebAssembly.Module.imports() API, Constructor, JavaScript, Method, Module, Object, Reference, WebAssembly, imports
The WebAssembly.imports() function returns an array containing descriptions of all the declared imports of the given Module.
809 WebAssembly.Module.prototype JavaScript, Module, Property, Prototype, WebAssembly
The WebAssembly.Module.prototype property represents the prototype for the WebAssembly.Module() constructor.
810 WebAssembly.RuntimeError() API, Constructor, JavaScript, Reference, RuntimeError, WebAssembly
The WebAssembly.RuntimeError() constructor creates a new WebAssembly RuntimeError object — the type that is thrown whenever WebAssembly specifies a trap.
811 WebAssembly.Table() API, Constructor, JavaScript, Object, Reference, WebAssembly, table
The WebAssembly.Table() constructor creates a new Table object of the given size and element type.
812 WebAssembly.Table.prototype JavaScript, Property, Prototype, WebAssembly, table
The WebAssembly.Table.prototype property represents the prototype for the WebAssembly.Table() constructor.
813 WebAssembly.Table.prototype.get() API, JavaScript, Method, Reference, WebAssembly, get, table
The get() prototype method of the WebAssembly.Table() object retrieves a function reference stored at a given index.
814 WebAssembly.Table.prototype.grow() API, JavaScript, Method, Reference, WebAssembly, grow, table
The grow() prototype method of the WebAssembly.Table object increases the size of the Table instance by a specified number of elements.
815 WebAssembly.Table.prototype.length API, JavaScript, Property, Reference, WebAssembly, length, table
The length prototype property of the WebAssembly.Table object returns the length of the table, i.e. the number of elements in the table.
816 WebAssembly.Table.prototype.set() API, JavaScript, Method, Reference, WebAssembly, set, table
The set() prototype method of the WebAssembly.Table object mutates a reference stored at a given index to a different value.
817 WebAssembly.compile() API, JavaScript, Method, Object, Reference, WebAssembly, compile
The WebAssembly.compile() function compiles a WebAssembly.Module from WebAssembly binary code.  This function is useful if it is necessary to a compile a module before it can be instantiated (otherwise, the WebAssembly.instantiate() function should be used).
818 WebAssembly.compileStreaming() API, Experimental, JavaScript, Method, Object, Reference, WebAssembly, compile, compileStreaming, streaming
The WebAssembly.compileStreaming() function compiles a WebAssembly.Module directly from a streamed underlying source.  This function is useful if it is necessary to a compile a module before it can be instantiated (otherwise, the WebAssembly.instantiateStreaming() function should be used).
819 WebAssembly.instantiate() API, JavaScript, Method, Object, Reference, WebAssembly, instantiate
The WebAssembly.instantiate() function allows you to compile and instantiate WebAssembly code. This function has two overloads:
820 WebAssembly.instantiateStreaming() API, JavaScript, Method, Object, Reference, WebAssembly, instantiate, instantiateStreaming, streaming
The WebAssembly.instantiateStreaming() function compiles and instantiates a WebAssembly module directly from a streamed underlying source. This is the most efficient, optimized way to load wasm code.
821 WebAssembly.validate() API, JavaScript, Method, Object, Reference, WebAssembly, validate
The WebAssembly.validate() function validates a given typed array of WebAssembly binary code, returning whether the bytes form a valid wasm module (true) or not (false).
822 decodeURI() Decode, JavaScript, String, Text, URI, URL, decodeURI, decoding
The decodeURI() function decodes a Uniform Resource Identifier (URI) previously created by encodeURI() or by a similar routine.
823 decodeURIComponent() JavaScript, Reference
The decodeURIComponent() function decodes a Uniform Resource Identifier (URI) component previously created by encodeURIComponent or by a similar routine.
824 encodeURI() Encoding, JavaScript, Text, URI, URL, encodeURI
The encodeURI() function encodes a Uniform Resource Identifier (URI) by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two "surrogate" characters).
825 encodeURIComponent() JavaScript, URI
The encodeURIComponent() function encodes a Uniform Resource Identifier (URI) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two "surrogate" characters).
826 escape() Deprecated, JavaScript
The escape() function computes a new string in which certain characters have been replaced by a hexadecimal escape sequence.
827 eval() Evaluating JavaScript, JavaScript, Reference, Warning, eval
The eval() function evaluates JavaScript code represented as a string.
828 globalThis JavaScript, Property, Reference, global, globalThis, this
The global globalThis property contains the global this value, which is akin to the global object.
829 isFinite() Functions, JavaScript, Reference, inFinite
The global isFinite() function determines whether the passed value is a finite number. If  needed, the parameter is first converted to a number.
830 isNaN() JavaScript, Method, Reference
The isNaN() function determines whether a value is NaN or not. Note, coercion inside the isNaN function has interesting rules; you may alternatively want to use Number.isNaN(), as defined in ECMAScript 2015.
831 null JavaScript, Literal, Primitive
The value null represents the intentional absence of any object value. It is one of JavaScript's primitive values and is treated as falsy for boolean operations.
832 parseFloat() JavaScript, Reference
The parseFloat() function parses an argument (converting it to a string first if needed) and returns a floating point number.
833 parseInt() JavaScript, Reference
The parseInt() function parses a string argument and returns an integer of the specified radix (the base in mathematical numeral systems).
834 undefined JavaScript
The global undefined property represents the primitive value undefined. It is one of JavaScript's primitive types.
835 unescape() Deprecated, JavaScript
The unescape() function computes a new string in which hexadecimal escape sequences are replaced with the character that it represents. The escape sequences might be introduced by a function like escape. Usually, decodeURI or decodeURIComponent are preferred over unescape.
836 uneval() Function, JavaScript, Non-standard, Reference, uneval
The uneval() function creates a string representation of the source code of an Object.
837 Statements and declarations JavaScript, Reference, statements
JavaScript applications consist of statements with an appropriate syntax. A single statement may span multiple lines. Multiple statements may occur on a single line if each statement is separated by a semicolon. This isn't a keyword, but a group of keywords.
838 Legacy generator function JavaScript, Legacy Iterator, Non-standard, Obsolete, Reference
The legacy generator function statement declares legacy generator functions with the specified parameters.
839 async function Example, Function, JavaScript, Statement
The async function declaration defines an asynchronous function — a function that returns an AsyncFunction object.
840 block JavaScript, Reference, Statement
A block statement (or compound statement in other languages) is used to group zero or more statements. The block is delimited by a pair of curly brackets and may optionally be labelled:
841 break JavaScript, Reference, Statement
The break statement terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.
842 class Classes, Declaration, ECMAScript 2015, JavaScript, Reference, Statement
The class declaration creates a new class with a given name using prototype-based inheritance.
843 const ECMAScript 2015, JavaScript, Reference, Statement, constants
Constants are block-scoped, much like variables defined using the let statement. The value of a constant can't be changed through reassignment, and it can't be redeclared.
844 continue JavaScript, Statement
The continue statement terminates execution of the statements in the current iteration of the current or labeled loop, and continues execution of the loop with the next iteration.
845 debugger JavaScript, Statement
The debugger statement invokes any available debugging functionality, such as setting a breakpoint. If no debugging functionality is available, this statement has no effect.
846 default JavaScript, Keyword
The default keyword can be used in two situations in JavaScript: within a switch statement, or with an export statement.
847 do...while JavaScript, Statement
The do...while statement creates a loop that executes a specified statement until the test condition evaluates to false. The condition is evaluated after executing the statement, resulting in the specified statement executing at least once.
848 empty JavaScript, Statement
An empty statement is used to provide no statement, although the JavaScript syntax would expect one.
849 export ECMAScript 2015, JavaScript, Modules, Statement, export
The export statement is used when creating JavaScript modules to export functions, objects, or primitive values from the module so they can be used by other programs with the import statement.
850 for JavaScript, Loop, Reference, Statement, for
The for statement creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement (usually a block statement) to be executed in the loop.
851 for await...of Iterate, Iteration, JavaScript, Reference, Statement, asynchronous, await
The for await...of statement creates a loop iterating over async iterable objects as well as on sync iterables, including: built-in String, Array, Array-like objects (e.g., arguments or NodeList), TypedArray, Map, Set, and user-defined async/sync iterables. It invokes a custom iteration hook with statements to be executed for the value of each distinct property of the object.
852 for each...in Deprecated, E4X, JavaScript, Obsolete, Statement
The for each...in statement iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.
853 for...in JavaScript, Statement
The for...in statement iterates over all non-Symbol, enumerable properties of an object.
854 for...of ECMAScript 2015, ES6, JavaScript, Reference, Statement
The for...of statement creates a loop iterating over iterable objects, including: built-in String, Array, array-like objects (e.g., arguments or NodeList), TypedArray, Map, Set, and user-defined iterables. It invokes a custom iteration hook with statements to be executed for the value of each distinct property of the object.
855 function declaration Function, JavaScript, Statement
The function declaration (function statement) defines a function with the specified parameters.
856 function* ECMAScript 2015, Function, Iterator, JavaScript, Statement
The function* declaration (function keyword followed by an asterisk) defines a generator function, which returns a Generator object.
857 if...else JavaScript, Reference, Statement, else, if
The if statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement can be executed.
858 import ECMAScript 2015, JavaScript, Modules, Reference, Statement, dynamic import, import
The static import statement is used to import bindings which are exported by another module.
859 import.meta JavaScript, Modules, Reference, Statement, import, import.meta
The import.meta object exposes context-specific metadata to a JavaScript module. It contains information about the module, like the module's URL.
860 label JavaScript, Statement
The labeled statement can be used with break or continue statements. It is prefixing a statement with an identifier which you can refer to.
861 let ECMAScript 2015, JavaScript, Statement, Variable declaration, Variables, let
The let statement declares a block scope local variable, optionally initializing it to a value.
862 return JavaScript, Statement
The return statement ends function execution and specifies a value to be returned to the function caller.
863 switch JavaScript, Reference, Statement, Web
The switch statement evaluates an expression, matching the expression's value to a case clause, and executes statements associated with that case, as well as statements in cases that follow the matching case.
864 throw JavaScript, Statement
The throw statement throws a user-defined exception. Execution of the current function will stop (the statements after throw won't be executed), and control will be passed to the first catch block in the call stack. If no catch block exists among caller functions, the program will terminate.
865 try...catch Error, Exception, JavaScript, Statement
The try...catch statement marks a block of statements to try, and specifies a response, should an exception be thrown.
866 var JavaScript, Reference, Statement
The var statement declares a variable, optionally initializing it to a value.
867 while JavaScript, Statement, while
The while statement creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated before executing the statement.
868 with Deprecated, JavaScript, Statement
The with statement extends the scope chain for a statement.
869 Strict mode ECMAScript 5, JavaScript, Strict Mode
JavaScript's strict mode, introduced in ECMAScript 5, is a way to opt in to a restricted variant of JavaScript, thereby implicitly opting-out of "sloppy mode". Strict mode isn't just a subset: it intentionally has different semantics from normal code. Browsers not supporting strict mode will run strict mode code with different behavior from browsers that do, so don't rely on strict mode without feature-testing for support for the relevant aspects of strict mode. Strict mode code and non-strict mode code can coexist, so scripts can opt into strict mode incrementally.
870 Transitioning to strict mode Advanced, JavaScript
ECMAScript 5 introduced strict mode which is now implemented in all major browsers (including IE10). While making web browsers interpret code as strict is easy (just add 'use strict'; at the top of your source code), transitioning an existing code base to strict mode requires a bit more work.
871 Template literals (Template strings) ECMAScript 2015, Guide, JavaScript, React, String, Template Strings, Template literals, Template string, strings, styled-components
Template literals are string literals allowing embedded expressions. You can use multi-line strings and string interpolation features with them. They were called "template strings" in prior editions of the ES2015 specification.
872 Trailing commas Comma, ECMAScript2017, ECMAScript5, JavaScript, Syntax, Trailing comma
Trailing commas (sometimes called "final commas") can be useful when adding new elements, parameters, or properties to JavaScript code. If you want to add a new property, you can simply add a new line without modifying the previously last line if that line already uses a trailing comma. This makes version-control diffs cleaner and editing code might be less troublesome.
873 JavaScript shells Extensions, JavaScript, Tools
A JavaScript shell allows you to quickly test snippets of JavaScript code without having to reload a web page. They are extremely useful for developing and debugging code.
874 JavaScript technologies overview Beginner, DOM, JavaScript
Whereas HTML defines a webpage's structure and content and CSS sets the formatting and appearance, JavaScript adds interactivity to a webpage and creates rich web applications.
875 JavaScript typed arrays Guide, JavaScript
JavaScript typed arrays are array-like objects that provide a mechanism for reading and writing raw binary data in memory buffers.
876 Memory Management Garbage collection, JavaScript, Performance, memory
Low-level languages like C, have manual memory management primitives such as malloc() and free(). In contrast, JavaScript automatically allocates memory when objects are created and frees it when they are not used anymore (garbage collection). This automaticity is a potential source of confusion: it can give developers the false impression that they don't need to worry about memory management.
877 Microsoft JavaScript extensions JavaScript, JavaScript:Microsoft Extensions, Non-standard, Reference
Microsoft browsers (Internet Explorer, and in a few cases, Microsoft Edge) support a number of special Microsoft extensions to the otherwise standard JavaScript APIs.
878 @cc_on JavaScript, JavaScript:Microsoft Extensions, Non-standard, Obsolete, Reference, Statement
The @cc_on statement activates conditional compilation support within comments in a script.
879 @if JavaScript, JavaScript:Microsoft Extensions, Non-standard, Obsolete, Reference, Statement
The @if statement conditionally executes a group of statements, depending on the value of an expression.
880 @set JavaScript, JavaScript:Microsoft Extensions, Non-standard, Obsolete, Reference, Statement
The @set statement creates variables used with conditional compilation statements.
881 ActiveXObject ActiveXObject, Deprecated, Extension, JavaScript, JavaScript:Microsoft Extensions, Microsoft, Non-standard, Obsolete, Reference
The ActiveXObject Object enables and returns a reference to an automation object.
882 Date.getVarDate() JavaScript, JavaScript:Microsoft Extensions, Method, Non-standard, Obsolete, Reference
The getVarDate method returns a VT_DATE value from a Date object.
883 Debug Debug, Interface, JavaScript, Non-standard
The debug object is an instrinsic global object that sends output to a debugger.
884 Debug.debuggerEnabled Debug, JavaScript, Property, Reference, debuggerEnabled
The debug.debuggerEnabled property determines whether debugging is enabled for the script context. Debugging may be enabled or disabled whether or not a debugger is attached.
885 Debug.msTraceAsyncCallbackCompleted Debug, JavaScript, NeedsContent, Property, Reference, msTraceAsyncCallbackCompleted
Indicates that the callback stack associated with a previously specified asynchronous operation has completed.
886 Debug.msTraceAsyncCallbackCompleted Debug, Example, JavaScript, Method, msTraceAsyncCallbackCompleted
The debug.msTraceAsyncCallbackCompleted function indicates that an asynchronous operation has completed.
887 Debug.msTraceAsyncCallbackStarting Debug, Example, JavaScript, Method, msTraceAsyncCallbackStarting
The debug.msTraceAsyncCallbackStarting function associates the callback stack with a previously specified asynchronous operation.
888 Debug.msTraceAsyncOperationStarting Debug, JavaScript, Method, Reference, msTraceAsyncOperationStarting
Initiates a trace for an asynchronous operation.
889 Debug.msUpdateAsyncCallbackRelation Debug, JavaScript, Method, Reference, msUpdateAsyncCallbackRelation
The debug.msUpdateAsyncCallbackRelation function updates the relationship status between a synchronous work item and the associated asynchronous operation.
890 Debug.setNonUserCodeExceptions Debug, Example, JavaScript, Property, setNonUserCodeExceptions
If this property is set to true within a given scope, the debugger can then choose whether to take some specified action on exceptions thrown inside that scope: for instance, if the developer wishes to break on user-unhandled exceptions. Setting this property to false is the same as never having set the property.
891 Debug.write Debug, Example, JavaScript, Method, write
The debug.write function sends strings to the script debugger.
892 Debug.writeln Beginner, JavaScript, Method
The debug.writeln function sends strings to the script debugger, followed by a newline character.
893 Enumerator JavaScript, Microsoft, enumerable
The Enumerator object enables enumeration of items in a collection.
894 Enumerator.atEnd Enumerator, Internet Explorer, JavaScript, Method, Non-standard, atEnd
The Enumerator.atEnd method returns a Boolean value indicating if the enumerator is at the end of the collection.
895 Enumerator.item Enumerator, JavaScript, Method
The Enumerator.item method returns the current item in the collection.
896 Enumerator.moveFirst Enumerator, Example, JavaScript, Method, Non-standard, moveFirst
The Enumerator.moveFirst method resets the current item in the collection to the first item.
897 Enumerator.moveNext Enumerator, Example, Internet Explorer, JavaScript, Method, Non-standard
The Enumerator.moveNext method moves the current item to the next item in the collection.
898 Error.description Error, Example, Internet Explorer, JavaScript, Non-standard, Property, description
The Error.description property returns or sets the descriptive string associated with a specific error.
899 Error.number Error, Example, Internet Explorer, JavaScript, Non-standard, Number, Property
The Error.number property returns or sets the numeric value associated with a specific error. The Error object's default property is number.
900 Error.stackTraceLimit Error, Example, Internet Explorer, JavaScript, Non-standard, Property, stackTraceLimit
The Error.stackTraceLimit property gets or sets the stack trace limit, which is equivalent to the number of error frames to display. The default limit is 10.
901 GetObject Example, JavaScript, Non-standard, Reference
The GetObject function returns a reference to an Automation object from a file.
902 ScriptEngine() Deprecated, JavaScript, JavaScript:Microsoft Extensions, Method, Non-standard
The ScriptEngine function gets the name of the scripting language in use.
903 ScriptEngineBuildVersion Example, Internet Explorer, JavaScript, Method, Non-standard, ScriptEngine, ScriptEngineBuildVersion
The ScriptEngineBuildVersion function bets the build version number of the scripting engine in use.
904 ScriptEngineMajorVersion Example, Internet Explorer, JavaScript, Method, Non-standard, ScriptEngine, ScriptEngineMajorVersion
The ScriptEngineMajorVersion function gets the major version number of the scripting engine in use.
905 ScriptEngineMinorVersion Example, Internet Explorer, JavaScript, Method, Non-standard, ScriptEngine, ScriptEngineMinorVersion
The ScriptEngineMinorVersion function gets the minor version number of the scripting engine in use.
906 VBArray Example, JavaScript, Non-standard, Reference
The VBArray object provides access to Visual Basic safe arrays.
907 VBArray.dimensions Example, JavaScript, Method, Non-standard, Reference
The VBArray.dimensions method returns the number of dimensions in a VBArray.
908 VBArray.getItem Example, JavaScript, Method, Non-standard, Reference
The VBArray.getItem method returns the item at the specified location.
909 VBArray.lbound Example, JavaScript, Method, Non-standard, Reference
The VBArray.lbound method returns the lowest index value used in the specified dimension of a VBArray.
910 VBArray.toArray Example, JavaScript, Method, Non-standard, Reference
The VBArray.toArray method returns a standard JavaScript array converted from a VBArray.
911 VBArray.ubound Example, JavaScript, Method, Non-standard, Reference
The VBArray.ubound method returns the highest index value used in the specified dimension of the VBArray.
912 New in JavaScript ECMAScript, JavaScript, Versions
This chapter contains information about JavaScript's version history and implementation status for Mozilla/SpiderMonkey-based JavaScript applications, such as Firefox.
913 ECMAScript 2015 support in Mozilla ECMAScript 2015, Firefox, JavaScript
ECMAScript 2015 is the sixth edition of the ECMAScript Language Specification standard. It defines the standard for the JavaScript implementation in SpiderMonkey, the engine used in Firefox and other Mozilla applications.
914 ECMAScript 5 support in Mozilla ECMAScript 5, JavaScript, Versions
ECMAScript 5.1, an older version of the standard upon which JavaScript is based, was approved in June 2011.
915 Firefox JavaScript changelog Firefox, JavaScript, NeedsUpdate, Versions
The following is a changelog for JavaScript features in Firefox releases.
916 New in JavaScript 1.1 JavaScript, Versions
The following is a changelog for JavaScript from Netscape Navigator 2.0 to 3.0. The old Netscape documentation references this as "Features added after version 1". Netscape Navigator 3.0 was released on August 19, 1996. Netscape Navigator 3.0 was the second major version of the browser with JavaScript support.
917 New in JavaScript 1.2 JavaScript, Versions
The following is a changelog for JavaScript from Netscape Navigator 3.0 to 4.0. The old Netscape documentation can be found on archive.org. Netscape Navigator 4.0 was released on June 11, 1997. Netscape Navigator 4.0 was the third major version of the browser with JavaScript support.
918 New in JavaScript 1.3 JavaScript, Versions
The following is a changelog for JavaScript from Netscape Navigator 4.0 to 4.5. The old Netscape documentation can be found on archive.org. Netscape Navigator 4.5 was released on October 19, 1998.
919 New in JavaScript 1.4 JavaScript, Versions
The following is a changelog for JavaScript 1.4, which was only used for Netscape's server side JavaScript released in 1999. The old Netscape documentation can be found on archive.org.
920 New in JavaScript 1.5 JavaScript, Versions
The following is a changelog for JavaScript 1.5. This version was included in Netscape Navigator 6.0 was released on November 14, 2000 and was also used in later versions of Netscape Navigator and Firefox 1.0. You can compare JavaScript 1.5 to JScript version 5.5 and Internet Explorer 5.5, which was released in July 2000. The corresponding ECMA standard is ECMA-262 Edition 3 (from December 1999).
921 New in JavaScript 1.6 JavaScript, Versions
The following is a changelog for JavaScript 1.6. This version was included in Firefox 1.5 (Gecko 1.8), which was released in November 2005. The corresponding ECMA standard is ECMA-262 Edition 3 and ECMAScript for XML (E4X) with some additional features. Several new features were introduced: E4X, several new Array methods, and Array and String generics.
922 New in JavaScript 1.7 JavaScript, Versions
The following is a changelog for JavaScript 1.7. This version was included in Firefox 2 (October 2006).
923 New in JavaScript 1.8 JavaScript, Versions
The following is a changelog for JavaScript 1.8. This version was included in Firefox 3 and is part of Gecko 1.9. See bug 380236 for a tracking development bug for JavaScript 1.8.
924 New in JavaScript 1.8.1 Firefox 3.5, JavaScript, Versions
The following is a changelog for JavaScript 1.8.1. This version was included in Firefox 3.5.
925 New in JavaScript 1.8.5 ECMAScript 5, Firefox 4, JavaScript, JavaScript 1.8.5, Versions
The following is a changelog for JavaScript 1.8.5. This version was included in Firefox 4.
926 The performance hazards of [[Prototype]] mutation JavaScript, Performance
Σχετικά θέματα
  1. JavaScript
  2. Tutorials:
  3. Complete beginners
    1. JavaScript basics
    2. JavaScript first steps
    3. JavaScript building blocks
    4. Introducing JavaScript objects
  4. JavaScript Guide
    1. Introduction
    2. Grammar and types
    3. Control flow and error handling
    4. Loops and iteration
    5. Functions
    6. Expressions and operators
    7. Numbers and dates
    8. Text formatting
    9. Regular expressions
    10. Indexed collections
    11. Keyed collections
    12. Working with objects
    13. Details of the object model
    14. Using promises
    15. Iterators and generators
    16. Meta programming
    17. JavaScript modules
  5. Intermediate
    1. Introducing JavaScript objects
    2. Client-side web APIs
    3. A re-introduction to JavaScript
    4. JavaScript data structures
    5. Equality comparisons and sameness
    6. Closures
  6. Advanced
    1. Inheritance and the prototype chain
    2. Strict mode
    3. JavaScript typed arrays
    4. Memory Management
    5. Concurrency model and Event Loop
  7. References:
  8. Built-in objects
    1. Array
    2. ArrayBuffer
    3. AsyncFunction
    4. Atomics
    5. BigInt
    6. BigInt64Array
    7. BigUint64Array
    8. Boolean
    9. DataView
    10. Date
    11. Error
    12. EvalError
    13. Float32Array
    14. Float64Array
    15. Function
    16. Generator
    17. GeneratorFunction
    18. Infinity
    19. Int16Array
    20. Int32Array
    21. Int8Array
    22. InternalError
    23. Intl
    24. Intl.Collator
    25. Intl.DateTimeFormat
    26. Intl.DisplayNames
    27. Intl.ListFormat
    28. Intl.Locale
    29. Intl.NumberFormat
    30. Intl.PluralRules
    31. Intl.RelativeTimeFormat
    32. JSON
    33. Map
    34. Math
    35. NaN
    36. Number
    37. Object
    38. Promise
    39. Proxy
    40. RangeError
    41. ReferenceError
    42. Reflect
    43. RegExp
    44. Set
    45. SharedArrayBuffer
    46. String
    47. Symbol
    48. SyntaxError
    49. TypeError
    50. TypedArray
    51. URIError
    52. Uint16Array
    53. Uint32Array
    54. Uint8Array
    55. Uint8ClampedArray
    56. WeakMap
    57. WeakSet
    58. WebAssembly
    59. decodeURI()
    60. decodeURIComponent()
    61. encodeURI()
    62. encodeURIComponent()
    63. escape()
    64. eval()
    65. globalThis
    66. isFinite()
    67. isNaN()
    68. null
    69. parseFloat()
    70. parseInt()
    71. undefined
    72. unescape()
    73. uneval()
  9. Expressions & operators
    1. Arithmetic operators
    2. Array comprehensions
    3. Assignment operators
    4. Bitwise operators
    5. Comma operator
    6. Comparison operators
    7. Conditional (ternary) operator
    8. Destructuring assignment
    9. Expression closures
    10. Function expression
    11. Generator comprehensions
    12. Grouping operator
    13. Legacy generator function expression
    14. Logical operators
    15. Nullish coalescing operator
    16. Object initializer
    17. Operator precedence
    18. Optional chaining
    19. Pipeline operator
    20. Property accessors
    21. Spread syntax
    22. async function expression
    23. await
    24. class expression
    25. delete operator
    26. function* expression
    27. in operator
    28. instanceof
    29. new operator
    30. new.target
    31. super
    32. this
    33. typeof
    34. void operator
    35. yield
    36. yield*
  10. Statements & declarations
    1. Legacy generator function
    2. async function
    3. block
    4. break
    5. class
    6. const
    7. continue
    8. debugger
    9. default
    10. do...while
    11. empty
    12. export
    13. for
    14. for await...of
    15. for each...in
    16. for...in
    17. for...of
    18. function declaration
    19. function*
    20. if...else
    21. import
    22. import.meta
    23. label
    24. let
    25. return
    26. switch
    27. throw
    28. try...catch
    29. var
    30. while
    31. with
  11. Functions
    1. Arrow function expressions
    2. Default parameters
    3. Method definitions
    4. Rest parameters
    5. The arguments object
    6. getter
    7. setter
  12. Classes
    1. Class fields
    2. constructor
    3. extends
    4. static
  13. Errors
    1. Error: Permission denied to access property "x"
    2. InternalError: too much recursion
    3. RangeError: argument is not a valid code point
    4. RangeError: invalid array length
    5. RangeError: invalid date
    6. RangeError: precision is out of range
    7. RangeError: radix must be an integer
    8. RangeError: repeat count must be less than infinity
    9. RangeError: repeat count must be non-negative
    10. ReferenceError: "x" is not defined
    11. ReferenceError: assignment to undeclared variable "x"
    12. ReferenceError: can't access lexical declaration`X' before initialization
    13. ReferenceError: deprecated caller or arguments usage
    14. ReferenceError: invalid assignment left-hand side
    15. ReferenceError: reference to undefined property "x"
    16. SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated
    17. SyntaxError: "use strict" not allowed in function with non-simple parameters
    18. SyntaxError: "x" is a reserved identifier
    19. SyntaxError: JSON.parse: bad parsing
    20. SyntaxError: Malformed formal parameter
    21. SyntaxError: Unexpected token
    22. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    23. SyntaxError: a declaration in the head of a for-of loop can't have an initializer
    24. SyntaxError: applying the 'delete' operator to an unqualified name is deprecated
    25. SyntaxError: for-in loop head declarations may not have initializers
    26. SyntaxError: function statement requires a name
    27. SyntaxError: identifier starts immediately after numeric literal
    28. SyntaxError: illegal character
    29. SyntaxError: invalid regular expression flag "x"
    30. SyntaxError: missing ) after argument list
    31. SyntaxError: missing ) after condition
    32. SyntaxError: missing : after property id
    33. SyntaxError: missing ; before statement
    34. SyntaxError: missing = in const declaration
    35. SyntaxError: missing ] after element list
    36. SyntaxError: missing formal parameter
    37. SyntaxError: missing name after . operator
    38. SyntaxError: missing variable name
    39. SyntaxError: missing } after function body
    40. SyntaxError: missing } after property list
    41. SyntaxError: redeclaration of formal parameter "x"
    42. SyntaxError: return not in function
    43. SyntaxError: test for equality (==) mistyped as assignment (=)?
    44. SyntaxError: unterminated string literal
    45. TypeError: "x" has no properties
    46. TypeError: "x" is (not) "y"
    47. TypeError: "x" is not a constructor
    48. TypeError: "x" is not a function
    49. TypeError: "x" is not a non-null object
    50. TypeError: "x" is read-only
    51. TypeError: 'x' is not iterable
    52. TypeError: More arguments needed
    53. TypeError: Reduce of empty array with no initial value
    54. TypeError: X.prototype.y called on incompatible type
    55. TypeError: can't access dead object
    56. TypeError: can't access property "x" of "y"
    57. TypeError: can't assign to property "x" on "y": not an object
    58. TypeError: can't define property "x": "obj" is not extensible
    59. TypeError: can't delete non-configurable array element
    60. TypeError: can't redefine non-configurable property "x"
    61. TypeError: cannot use 'in' operator to search for 'x' in 'y'
    62. TypeError: cyclic object value
    63. TypeError: invalid 'instanceof' operand 'x'
    64. TypeError: invalid Array.prototype.sort argument
    65. TypeError: invalid arguments
    66. TypeError: invalid assignment to const "x"
    67. TypeError: property "x" is non-configurable and can't be deleted
    68. TypeError: setting getter-only property "x"
    69. TypeError: variable "x" redeclares argument
    70. URIError: malformed URI sequence
    71. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    72. Warning: 08/09 is not a legal ECMA-262 octal constant
    73. Warning: Date.prototype.toLocaleFormat is deprecated
    74. Warning: JavaScript 1.6's for-each-in loops are deprecated
    75. Warning: String.x is deprecated; use String.prototype.x instead
    76. Warning: expression closures are deprecated
    77. Warning: unreachable code after return statement
  14. Misc
    1. JavaScript technologies overview
    2. Lexical grammar
    3. JavaScript data structures
    4. Enumerability and ownership of properties
    5. Iteration protocols
    6. Strict mode
    7. Transitioning to strict mode
    8. Template literals
    9. Deprecated features
  15. New in JavaScript
    1. ECMAScript 2015 support in Mozilla
    2. ECMAScript 5 support in Mozilla
    3. Firefox JavaScript changelog
    4. New in JavaScript 1.1
    5. New in JavaScript 1.2
    6. New in JavaScript 1.3
    7. New in JavaScript 1.4
    8. New in JavaScript 1.5
    9. New in JavaScript 1.6
    10. New in JavaScript 1.7
    11. New in JavaScript 1.8
    12. New in JavaScript 1.8.1
    13. New in JavaScript 1.8.5
  16. Documentation:
  17. Useful lists
    1. All pages index
    2. Methods index
    3. Properties index
    4. Pages tagged "JavaScript"
  18. Contribute
    1. JavaScript doc status
    2. The MDN project