Web/JavaScript/Reference/Global objects/Symbol/keyFor

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

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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()

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

var 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 (ECMA-262)The definition of 'Symbol.keyFor' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`keyFor`	Chrome Full support 40	Edge Full support 12	Firefox Full support 36	IE No support No	Opera Full support 27	Safari Full support 9	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 36	Opera Android Full support 27	Safari iOS Full support 9	Samsung Internet Android Full support 4.0	nodejs Full support 0.12

Legend

Full support: Full support
No support: No support