es-toolkit/docs/reference/predicate/isNil.md

isNil

Checks if a given value is null or undefined.

This function tests whether the provided value is either null or undefined. It returns true if the value is null or undefined, and false otherwise.

This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to null or undefined.

Signature

function isNil(x: unknown): x is null | undefined;

Examples

import { isNil } from 'es-toolkit/predicate';

const value1 = null;
const value2 = undefined;
const value3 = 42;
const result1 = isNil(value1); // true
const result2 = isNil(value2); // true
const result3 = isNil(value3); // false