Symbol.keyFor()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It's been available across browsers since September 2015.

The Symbol.keyFor() static method retrieves a shared symbol key from the global symbol registry for the given symbol.

Try it

const globalSym = Symbol.for("foo"); // Global symbol

console.log(Symbol.keyFor(globalSym));
// Expected output: "foo"

const localSym = Symbol(); // Local symbol

console.log(Symbol.keyFor(localSym));
// Expected output: undefined

console.log(Symbol.keyFor(Symbol.iterator));
// Expected output: undefined

Syntax

Symbol.keyFor(sym)

Parameters

sym: Symbol, required. The symbol to find a key for.

Return value

A string representing the key for the given symbol if one is found on the global registry; otherwise, undefined.

Examples

Using keyFor()

const globalSym = Symbol.for("foo"); // create a new global symbol
Symbol.keyFor(globalSym); // "foo"

const localSym = Symbol();
Symbol.keyFor(localSym); // undefined

// well-known symbols are not symbols registered
// in the global symbol registry
Symbol.keyFor(Symbol.iterator); // undefined

Specifications

Specification
ECMAScript® 2027 Language Specification # sec-symbol.keyfor

Browser compatibility

	Desktop					Mobile							Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`keyFor`	40	12	36	27	9	40	36	27	9	4.0	40	9	1.0.0	1.0	0.12.0