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

isNull

Checks if the given value is null.

This function tests whether the provided value is strictly equal to null. It returns true if the value is null, and false otherwise.

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

Signature

function isNull(x: unknown): x is null;

Parameters

• x (unknown): The value to test if it is null.

Returns

(x is null): True if the value is null, false otherwise.

Examples

const value1 = null;
const value2 = undefined;
const value3 = 42;

console.log(isNull(value1)); // true
console.log(isNull(value2)); // false
console.log(isNull(value3)); // false