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javascript static method

Symbol.keyFor()

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

Interactive exampleOpen the canonical MDN source to run this embedded demo.
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

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also