What you should already know
println might have been defined as follows:
Mapping to equivalent functionality in other environments is left as an exercise for the reader.
This reference includes descriptive syntax sections to demonstrate appropriate or common usage of the subject of documentation. Within these sections, all text literals to be reproduced verbatim are non-italicized, with the exception of ellipses. Words in italics represent user-defined names or statements. Any portions enclosed in square brackets (
]) are optional. A comma-delimited sequence that includes an ellipsis (
...) indicates that the sequence is a list and all items in the sequence except the first are optional (e.g. only
param1 is required in "
param1, param2, ..., paramN").
Global properties returning a simple value.
Global functions returning the result of a specific routine.
General language objects, functions and errors.
Numbers and dates
Objects dealing with numbers, dates and mathematical calculations.
Objects for manipulating texts.
Collections ordered by an index. Array-type objects.
Collections of objects as keys. Elements iterable in insertion order.
Control abstraction objects
Additions to the ECMAScript core for language-sensitive functionalities.
- Generators functions enable writing iterators more easily.
- A block statement is used to group zero or more statements. The block is delimited by a pair of curly brackets.
- Terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.
- Declares a read-only named constant.
- Terminates execution of the statements in the current iteration of the current or labelled loop, and continues execution of the loop with the next iteration.
- Invokes any available debugging functionality. If no debugging functionality is available, this statement has no effect.
- 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.
- Allows a signed script to provide properties, functions, and objects to other signed or unsigned scripts. This feature is not in ECMA-262, Edition 3.
- Creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
- Iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.
- Iterates over the enumerable properties of an object, in arbitrary order. For each distinct property, statements can be executed.
- Iterates over iterable objects (including arrays, array-like objects, iterators and generators), invoking a custom iteration hook with statements to be executed for the value of each distinct property.
- Declares a function with the specified parameters.
- Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.
- Allows a script to import properties, functions, and objects from a signed script that has exported the information. This feature is not in ECMA 262, Edition 3.
- Provides a statement with an identifier that you can refer to using a
- Declares a block scope local variable, optionally initializing it to a value.
- Specifies the value to be returned by a function.
- Evaluates an expression, matching the expression's value to a case clause, and executes statements associated with that case.
- Throws a user-defined exception.
- Marks a block of statements to try, and specifies a response, should an exception be thrown.
- Declares a variable, optionally initializing it to a value.
- 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.
- Extends the scope chain for a statement.
There are several special operators that do not fit into any other category:
- Arithmetic Operators
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.
- Assignment Operators
=, *=, /=, %=, +=, -=, <<=, >>=, >>>=, &=, ^=, |=)
An assignment operator assigns a value to its left operand based on the value of its right operand.
- Bitwise Operators
- Comparison Operators
A comparison operator compares its operands and returns a logical value based on whether the comparison is true.
- Logical Operators
Logical operators are typically used with boolean (logical) values, and when they are, they return a boolean value.
- String Operators
The string operators concatenate two string values together, returning another string that is the union of the two strings.
- Member Operators
Member operators provide access to a property or method of an object.
- Special Operators
- Conditional Operator
condition ? ifTrue : ifFalse)
The conditional operator returns one of two values based on the logical value of the condition.
- Comma Operator
The comma operator allows multiple expressions to be evaluated in a single statement and returns the result of the last expression.
- delete Operator
The delete operator deletes a property from an object.
- in Operator
The in operator determines whether an object has a given property.
- instanceof Operator
The instanceof operator determines whether an object is an instance of another object.
- new Operator
The new operator creates an instance of a constructor.
- Operator Precedence
- Operator precedence defines the order in which operators are evaluated.
- get Modifier
The get modifier defines a property in an object literal to be a getter.
- set Modifier
The set modifier defines a property in an object literal to be a setter.
- function Keyword
The function keyword defines a function expression.
- this Keyword
The this keyword refers to the function's execution context.
- Code comments (