JavaScript reference

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
  • 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
  • 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