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

js
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()

js
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® 2025 Language Specification
# sec-symbol.keyfor

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
keyFor

Legend

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Full support
Full support

See also