Symbol.for()
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.for()
static method searches for existing symbols
in a runtime-wide symbol registry with the given key and returns it if found. Otherwise
a new symbol gets created in the global symbol registry with this key.
Try it
console.log(Symbol.for("bar") === Symbol.for("bar"));
// Expected output: true
console.log(Symbol("bar") === Symbol("bar"));
// Expected output: false
const 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 the symbol).
Return value
An existing symbol with the given key if found; otherwise, a new symbol is created and returned.
Description
In contrast to Symbol()
, the Symbol.for()
function creates a
symbol available in a global symbol registry list. Symbol.for()
does also
not necessarily create a new symbol on every call, but checks first if a symbol with the
given key
is already present in the registry. In that case, that symbol is
returned. If no symbol with the given key is found, Symbol.for()
will
create a new global symbol.
Examples
Using Symbol.for()
Symbol.for("foo"); // create a new global symbol
Symbol.for("foo"); // retrieve the already created symbol
// Same global symbol, but not locally
Symbol.for("bar") === Symbol.for("bar"); // true
Symbol("bar") === Symbol("bar"); // false
// The key is also used as the description
const sym = Symbol.for("mario");
sym.toString(); // "Symbol(mario)"
To avoid name clashes with your global symbol keys and other (library code) global symbols, it might be a good idea to prefix your symbols:
Symbol.for("mdn.foo");
Symbol.for("mdn.bar");
Specifications
Specification |
---|
ECMAScript® 2025 Language Specification # sec-symbol.for |
Browser compatibility
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- Full support
- Full support