nonNumberLike
function nonNumberLike(value: unknown): boolean;
nonNumberLike(value) is the same test as !isNumberLike(value), written so that a guard clause reads as a sentence rather than as a negation.
A finite number, or a string that converts to one. NaN, the infinities and the empty string are excluded, which is what separates this from a bare Number(value).
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 convertible to a number; otherwise false.
Examples
What passes and what does not
nonNumberLike(NaN); // => true
nonNumberLike(Infinity); // => true
nonNumberLike(""); // => true
nonNumberLike(null); // => true
nonNumberLike(1); // => false
nonNumberLike("1.5"); // => false
nonNumberLike(" 42 "); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.