mozilla
Your Search Results

    JavaScript リファレンス

    This article is in need of an editorial review.

    This translation is incomplete. Please help translate this article from English.

    このJavaScriptのセクションは、JavaScriptについて実際のリポジトリとして役に立ちます。 さらには、こちらのリファレンスを参照して下さい。

    Global Objects

    この章では、 JavaScript 標準 built-in objectsについて、メソッドとプロパティと共に、記載されています。

    Value properties

    These global properties return a simple value; they have no properties or methods.

    Function properties

    These global functions—functions which are called globally rather than on an object—directly return their results to the caller.

    Fundamental objects

    These are the fundamental, basic objects upon which all other objects are based. This includes objects that represent general objects, functions, and errors.

    Numbers and dates

    These are the base objects representing numbers, dates, and mathematical calculations.

    Text processing

    These objects represent strings and support manipulating them.

    Indexed collections

    These objects represent collections of data which are ordered by an index value. This includes arrays and array-like constructs.

    Keyed collections

    These objects represent collections which use keys; these contain elements which are iterable in the order of insertion.

    Structured data

    These objects represent and interact with structured data buffers and data coded using JavaScript Object Notation (JSON).

    Control abstraction objects

    Reflection

    Internationalization

    Additions to the ECMAScript core for language-sensitive functionalities.

    Non-standard objects

    Other

    Statements

    この章では、JavaScript statements and declarationsについて、記載されています。

    For an alphabetical listing see the sidebar on the left.

    Control flow

    Block
    A block statement is used to group zero or more statements. The block is delimited by a pair of curly brackets.
    break
    Terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.
    continue
    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.
    Empty
    An empty statement is used to provide no statement, although the JavaScript syntax would expect one.
    if...else
    Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.
    switch
    Evaluates an expression, matching the expression's value to a case clause, and executes statements associated with that case.
    throw
    Throws a user-defined exception.
    try...catch
    Marks a block of statements to try, and specifies a response, should an exception be thrown.

    Declarations

    var
    Declares a variable, optionally initializing it to a value.
    let
    Declares a block scope local variable, optionally initializing it to a value.
    const
    Declares a read-only named constant.

    Functions and classes

    function
    Declares a function with the specified parameters.
    function*
    Generators functions enable writing iterators more easily.
    return
    Specifies the value to be returned by a function.
    class
    Declares a class.

    Iterations

    do...while
    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.
    for
    Creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
    for each...in
    Iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.
    for...in
    Iterates over the enumerable properties of an object, in arbitrary order. For each distinct property, statements can be executed.
    for...of
    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.
    while
    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.

    Others

    debugger
    Invokes any available debugging functionality. If no debugging functionality is available, this statement has no effect.
    export
    Used to export functions to make them available for imports in external modules, another scripts.
    import
    Used to import functions exported from an external module, another script.
    label
    Provides a statement with an identifier that you can refer to using a break or continue statement.
    with
    Extends the scope chain for a statement.

    Expressions and operators

    この章では、JavaScript expressions and operatorsについて、記載されています。

    For an alphabetical listing see the sidebar on the left.

    Primary expressions

    Basic keywords and general expressions in JavaScript.

    this
    The this keyword refers to the function's execution context.
    function
    The function keyword defines a function expression.
    class
    The class keyword defines a class expression.
    function*
    The function* keyword defines a generator function expression.
    yield
    Pause and resume a generator function
    yield*
    Delegate to another generator function or iterable object.
    []
    Array initializer/literal syntax.
    {}
    Object initializer/literal syntax.
    /ab+c/i
    Regular expression literal syntax.
    [for (x of y) x]
    Array comprehensions.
    (for (x of y) y)
    Generator comprehensions.
    ( )
    Grouping operator.

    Left-hand-side expressions

    Left values are the destination of an assignment.

    Property accessors
    Member operators provide access to a property or method of an object
    (object.property and object["property"]).
    new
    The new operator creates an instance of a constructor.
    super
    The super keyword calls the parent constructor.
    ...obj
    The spread operator allows an expression to be expanded in places where multiple arguments (for function calls) or multiple elements (for array literals) are expected.

    Increment and decrement

    Postfix/prefix increment and postfix/prefix decrement operators.

    A++
    Postfix increment operator.
    A--
    Postfix decrement operator.
    ++A
    Prefix increment operator.
    --A
    Prefix decrement operator.

    Unary operators

    A unary operation is operation with only one operand.

    delete
    The delete operator deletes a property from an object.
    void
    The void operator discards an expression's return value.
    typeof
    The typeof operator determines the type of a given object.
    +
    The unary plus operator converts its operand to Number type.
    -
    The unary negation operator converts its operand to Number type and then negates it.
    ~
    Bitwise NOT operator.
    !
    Logical NOT operator.

    Arithmetic operators

    Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.

    +
    Addition operator.
    -
    Subtraction operator.
    /
    Division operator.
    *
    Multiplication operator.
    %
    Remainder operator.

    Relational operators

    A comparison operator compares its operands and returns a Boolean value based on whether the comparison is true.

    in
    The in operator determines whether an object has a given property.
    instanceof
    The instanceof operator determines whether an object is an instance of another object.
    <
    Less than operator.
    >
    Greater than operator.
    <=
    Less than or equal operator.
    >=
    Greater than or equal operator.

    Equality operators

    The result of evaluating an equality operator is always of type Boolean based on whether the comparison is true.

    ==
    Equality operator.
    !=
    Inequality operator.
    ===
    Identity operator.
    !==
    Nonidentity operator.

    Bitwise shift operators

    Operations to shift all bits of the operand.

    <<
    Bitwise left shift operator.
    >>
    Bitwise right shift operator.
    >>>
    Bitwise unsigned right shift operator.

    Binary bitwise operators

    Bitwise operators treat their operands as a set of 32 bits (zeros and ones) and return standard JavaScript numerical values.

    &
    Bitwise AND.
    |
    Bitwise OR.
    ^
    Bitwise XOR.

    Binary logical operators

    Logical operators are typically used with boolean (logical) values, and when they are, they return a boolean value.

    &&
    Logical AND.
    ||
    Logical OR.

    Conditional (ternary) operator

    (condition ? ifTrue : ifFalse)

    The conditional operator returns one of two values based on the logical value of the condition.

    Assignment operators

    An assignment operator assigns a value to its left operand based on the value of its right operand.

    =
    Assignment operator.
    *=
    Multiplication assignment.
    /=
    Division assignment.
    %=
    Remainder assignment.
    +=
    Addition assignment.
    -=
    Subtraction assignment
    <<=
    Left shift assignment.
    >>=
    Right shift assignment.
    >>>=
    Unsigned right shift assignment.
    &=
    Bitwise AND assignment.
    ^=
    Bitwise XOR assignment.
    |=
    Bitwise OR assignment.
    [a, b] = [1, 2]
    {a, b} = {a:1, b:2}

    Destructuring assignment allows you to assign the properties of an array or object to variables using syntax that looks similar to array or object literals.

    Comma operator

    ,
    The comma operator allows multiple expressions to be evaluated in a single statement and returns the result of the last expression.

    Non-standard features

    Legacy generator function
    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 contains at least one yield expression.
    Expression closures
    The expression closure syntax is a shorthand for writing simple function.

    Functions

    この章では、アプリケーションを開発する際の、JavaScript functions の使い方について、記載されています。

    追加リファレンスページ

    ドキュメントのタグと貢献者

    最終更新者: shide55,
    サイドバーを隠す