nonFunctionLike
function nonFunctionLike<T>(value: T | Function): value is T;
nonFunctionLike(value) is the same test as !isFunctionLike(value), written so that a guard clause reads as a sentence rather than as a negation.
The cheap test — typeof value === "function" — which is what you want before calling something. isFunction is the stricter reading of the same question.
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 not callable; otherwise false.
In TypeScript the guard narrows value to T inside the branch.
Examples
What passes and what does not
nonFunctionLike(null); // => true
nonFunctionLike({}); // => true
nonFunctionLike("fn"); // => true
nonFunctionLike(function () {}); // => false
nonFunctionLike(Math.max); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.