nonNil
function nonNil<T>(value: T | null | undefined): value is T;
nonNil(value) is the same test as !isNil(value), written so that a guard clause reads as a sentence rather than as a negation.
The absent values, and only those: 0, "" and false are present values and do not qualify.
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 null or undefined; otherwise false.
In TypeScript the guard narrows value to T inside the branch.
Examples
What passes and what does not
nonNil(0); // => true
nonNil(""); // => true
nonNil(false); // => true
nonNil(null); // => false
nonNil(undefined); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.