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Supported engines and compatibility data
Features
ECMAScript
ECMAScript: Object
ECMAScript: Function
ECMAScript: Error
ECMAScript: Array
ECMAScript: Iterator
ECMAScript: String and RegExp
ECMAScript: Number
ECMAScript: Math
ECMAScript: Date
ECMAScript: Promise
ECMAScript: Symbol
ECMAScript: Collections
ECMAScript: Explicit Resource Management
ECMAScript: Typed Arrays
ECMAScript: Reflect
ECMAScript: JSON
ECMAScript: globalThis
ECMAScript proposals
Finished proposals
globalThis
Relative indexing method
Array.prototype.includes
Array.prototype.flat / Array.prototype.flatMap
Array find from last
Change Array by copy
Array grouping
Array.fromAsync
ArrayBuffer.prototype.transfer and friends
Uint8Array to / from base64 and hex
Error.isError
Explicit Resource Management
Float16 methods
Iterator helpers
Iterator sequencing
Object.values / Object.entries
Object.fromEntries
Object.getOwnPropertyDescriptors
Accessible Object.prototype.hasOwnProperty
String padding
String.prototype.matchAll
String.prototype.replaceAll
String.prototype.trimStart / String.prototype.trimEnd
RegExp s (dotAll) flag
RegExp named capture groups
RegExp escaping
Promise.allSettled
Promise.any
Promise.prototype.finally
Promise.try
Promise.withResolvers
Symbol.asyncIterator for asynchronous iteration
Symbol.prototype.description
JSON.parse source text access
Well-formed JSON.stringify
Well-formed unicode strings
New Set methods
Math.sumPrecise
Stage 3 proposals
Joint iteration
Map upsert
Symbol.metadata for decorators metadata proposal
Stage 2.7 proposals
Iterator chunking
Iterator join
Await dictionary
Stage 2 proposals
AsyncIterator helpers
Iterator.range
Array.isTemplateObject
Number.prototype.clamp
String.dedent
Symbol predicates
Symbol.customMatcher for extractors
Stage 1 proposals
.of and .from methods on collection constructors
Array filtering
Array deduplication
DataView get / set Uint8Clamped methods
String.cooked
Symbol.customMatcher for pattern matching
Stage 0 proposals
Function.prototype.demethodize
Web standards
self
structuredClone
Base64 utility methods
setImmediate
queueMicrotask
URL and URLSearchParams
DOMException
Iterable DOM collections
Iteration helpers
Missing polyfills
Contributing
Security Policy
globalThis
Specification
Proposal repo
Built-ins signatures
let globalThis: GlobalThisValue;
Entry points
core-js/proposals/global-this
Built-ins signatures
Entry points