JavaScript reference - JavaScript 编辑

This part of the JavaScript section on MDN serves as a repository of facts about the JavaScript language. Read more about this reference.

Built-ins

JavaScript standard built-in objects, along with their methods and properties.

Value properties

• Infinity
• NaN
• undefined
• globalThis

Function properties

• eval()
• isFinite()
• isNaN()
• parseFloat()
• parseInt()
• decodeURI()
• decodeURIComponent()
• encodeURI()
• encodeURIComponent()

Fundamental objects

• Object
• Function
• Boolean
• Symbol

Error objects

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

Numbers & dates

• Number
• BigInt
• Math
• Date

Text processing

• String
• RegExp

Indexed Collections

• Array
• Int8Array
• Uint8Array
• Uint8ClampedArray
• Int16Array
• Uint16Array
• Int32Array
• Uint32Array
• Float32Array
• Float64Array
• BigInt64Array
• BigUint64Array

Keyed collections

• Map
• Set
• WeakMap
• WeakSet

Structured data

• ArrayBuffer
• SharedArrayBuffer
• Atomics
• DataView
• JSON

Control abstraction

• GeneratorFunction
• AsyncGeneratorFunction
• Generator
• AsyncGenerator
• AsyncFunction
• Promise

Reflection

• Reflect
• Proxy

Internationalization

• Intl
• Intl.Collator
• Intl.DateTimeFormat
• Intl.DisplayNames
• Intl.ListFormat
• Intl.Locale
• Intl.NumberFormat
• Intl.PluralRules
• Intl.RelativeTimeFormat

WebAssembly

• WebAssembly
• WebAssembly.Module
• WebAssembly.Instance
• WebAssembly.Memory
• WebAssembly.Table
• WebAssembly.CompileError
• WebAssembly.LinkError
• WebAssembly.RuntimeError

Statements

JavaScript statements and declarations

Control flow

• Block
• break
• continue
• Empty
• if...else
• switch
• throw
• try...catch

Declarations

• var
• let
• const

Functions and classes

• function
• function*
• async function
• return
• class

Iterations

• do...while
• for
• for each...in
• for...in
• for...of
• for await...of
• while

Other

• debugger
• export
• import
• label
• with

Expressions and operators

JavaScript expressions and operators. 

Primary expressions

• this
• function
• class
• function*
• yield
• yield*
• async function
• await
• []
• {}
• /ab+c/i
• ( )
• null

Left-hand-side expressions

• Property accessors
• new
• new.target
• import.meta
• super
• ...obj

Increment & decrement

• A++
• A--
• ++A
• --A

Unary operators

• delete
• void
• typeof
• +
• -
• ~
• !

Arithmetic operators

• +
• -
• /
• *
• %
• **

Relational operators

• in
• instanceof
• <
• >
• <=
• >=

Equality operators

• ==
• !=
• ===
• !==

Bitwise shift operators

• <<
• >>
• >>>

Binary bitwise operators

• &
• |
• ^

Binary logical operators

• &&
• ||

Conditional (ternary) operator

• (condition ? ifTrue : ifFalse)

Assignment operators

• =
• *=
• /=
• %=
• +=
• -=
• <<=
• >>=
• >>>=
• &=
• ^=
• |=
• [a, b] = [1, 2]
• {a, b} = {a:1, b:2}

Functions

This chapter documents how to work with JavaScript functions to develop your applications.

• arguments
• Arrow functions
• Default parameters
• Rest parameters

Additional reference pages

• Lexical grammar
• Data types and data structures
• Strict mode
• Deprecated features