Table of contents

1. 1.About this Reference
2. 2.Global Objects
   1. 2.1.Standard global objects (by category)
      1. 2.1.1.General-purpose constructors
      2. 2.1.2.Typed array constructors
      3. 2.1.3.Error constructors
      4. 2.1.4.Non-constructor functions
      5. 2.1.5.Other
   2. 2.2.Standard global objects (alphabetically)
3. 3.Functions and function scope
4. 4.Statements
5. 5.Operators and other keywords
6. 6.Comments
7. 7.E4X (extension)
8. 8.Appendix A - Reserved Words
9. 9.Appendix B - Deprecated Features

About this Reference

Global Objects

Standard global objects (by category)

General-purpose constructors

• Array
• Boolean
• Date
• Function
• Iterator
• Number
• Object
• RegExp
• String

Typed array constructors

• ArrayBuffer
• Float32Array
• Float64Array
• Int16Array
• Int32Array
• Int8Array
• Uint16Array
• Uint32Array
• Uint8Array
• Uint8ClampedArray

Error constructors

• Error
• EvalError
• InternalError
• RangeError
• ReferenceError
• StopIteration
• SyntaxError
• TypeError
• URIError

Non-constructor functions

• decodeURI
• decodeURIComponent
• encodeURI
• encodeURIComponent
• eval
• isFinite
• isNaN
• parseFloat
• parseInt
• uneval

Other

• Infinity
• JSON
• Math
• NaN
• undefined

Standard global objects (alphabetically)

• Array
• ArrayBuffer
• Boolean
• Date
• decodeURI
• decodeURIComponent
• encodeURI
• encodeURIComponent
• Error
• eval
• EvalError
• Float32Array
• Float64Array
• Function
• Infinity
• Int16Array
• Int32Array
• Int8Array
• isFinite
• isNaN
• Iterator
• JSON
• Math
• NaN
• Number
• Object
• parseFloat
• parseInt
• RangeError
• ReferenceError
• RegExp
• StopIteration
• String
• SyntaxError
• TypeError
• Uint16Array
• Uint32Array
• Uint8Array
• Uint8ClampedArray
• undefined
• uneval
• URIError

Other objects in the global scope are eithercreated by the user script or provided by the host application. The host objects available inGecko-based browsers are documented in theGecko DOM Reference.

For more information about the distinction between theDOM and coreJavaScript, seeThe DOM and JavaScript article.

Functions and function scope

• arguments
• Strict mode

Statements

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.

const

Declares a read-only, named constant.

continue

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.

debugger

Invokes any available debugging functionality. If no debugging functionality is available, this statement has no effect.

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.

export

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.

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...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.

for each...in

Iterates a specified variable over all values of object's properties. For each distinct property, a specified statement is executed.

function

Declares a function with the specified parameters.

if...else

Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.

import

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.

label

Provides a statement with an identifier that you can refer to using a break or continue statement.

let

Declares a block scope local variable, optionally initializing it to a value.

return

Specifies the value to be returned by a function.

switch

Evaluates an expression, matching the expression's value to a case label, 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.

var

Declares a variable, optionally initializing it to a value.

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.

with

Extends the scope chain for a statement.

yield

yield

Operators and other keywords

Arithmetic Operators

(+,-,*,/,%,++,--, unary-, unary +)

Assignment Operators

(=, *=, /=, %=, +=, -=, <<=, >>=, >>>=, &=, ^=, |=)

Bitwise Operators

(&,|,^,~,<<,>>,>>>)

Comparison Operators

(==,!=,===,!==,>,>=,<,<=)

Logical Operators

(&&,||,!)

String Operators

(+ and+=)

Member Operators

(object.property andobject["property"])

Special Operators

Conditional Operator

(condition ?ifTrue :ifFalse)

Comma Operator

(,)

delete Operator

(delete)

function Operator

(function)

get Operator

(get)

in Operator

(in)

instanceof Operator

(instanceof)

let Operator

(let)

new Operator

(new)

set Operator

(set)

this Operator

(this)

typeof Operator

(typeof)

void Operator

(void)

yield Operator

(yield)

Operator Precedence

Operator precedence defines the order in which operators are evaluated.

Comments

• Code comments (// and/* */)

E4X (extension)

Global statements:

• default XML namespace

Global functions:

• isXMLName()

Global constructors:

• Namespace()
• QName()
• XML()
• XMLList()

Appendix A - Reserved Words

Appendix B - Deprecated Features