isSymbol
function isSymbol(value: unknown): value is symbol;
Registered symbols from Symbol.for and the well-known symbols both pass; nothing else does.
isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.
Parameters
Parameter | Type | Description |
|---|---|---|
|
| The value to check. |
Returns
boolean — true when the value is a symbol; otherwise false.
In TypeScript the guard narrows value to symbol inside the branch.
Examples
What passes and what does not
isSymbol(Symbol("id")); // => true
isSymbol(Symbol.iterator); // => true
isSymbol("id"); // => false
isSymbol(null); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.