Symbol.keyFor()

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

{{InteractiveExample("JavaScript Demo: Symbol.keyFor()")}}

```js interactive-example 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-nolint
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, {{jsxref("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#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Symbol.for()")}}