TheSymbol.for() static method searches for existing symbolsin a runtime-wide symbol registry with the given key and returns it if found. Otherwisea new symbol gets created in the global symbol registry with this key.

Try it

console.log(Symbol.for("bar") === Symbol.for("bar"));// Expected output: trueconsole.log(Symbol("bar") === Symbol("bar"));// Expected output: falseconst symbol1 = Symbol.for("foo");console.log(symbol1.toString());// Expected output: "Symbol(foo)"

Syntax

Symbol.for(key)

Parameters

key

String, required. The key for the symbol (and also used for the description of thesymbol).

Return value

An existing symbol with the given key if found; otherwise, a new symbol is created andreturned.

Description

In contrast toSymbol(), theSymbol.for() function creates asymbol available in aglobal symbol registry list.Symbol.for() does alsonot necessarily create a new symbol on every call, but checks first if a symbol with thegivenkey is already present in the registry. In that case, that symbol isreturned. If no symbol with the given key is found,Symbol.for() willcreate a new global symbol.

Examples

Using Symbol.for()

Symbol.for("foo"); // create a new global symbolSymbol.for("foo"); // retrieve the already created symbol// Same global symbol, but not locallySymbol.for("bar") === Symbol.for("bar"); // trueSymbol("bar") === Symbol("bar"); // false// The key is also used as the descriptionconst sym = Symbol.for("mario");sym.toString(); // "Symbol(mario)"

To avoid name clashes with your global symbol keys and other (library code) globalsymbols, it might be a good idea to prefix your symbols:

Symbol.for("mdn.foo");Symbol.for("mdn.bar");

Specifications

Browser compatibility

See also

• Symbol.keyFor()