isNil

Checks if a value is null or undefined.

typescript

const result = isNil(value);

Usage

`isNil(value)`

Use isNil when you want to check if a value is null or undefined.

typescript

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

// null or undefined values
console.log(isNil(null)); // true
console.log(isNil(undefined)); // true

// Other values
console.log(isNil(0)); // false
console.log(isNil('')); // false
console.log(isNil(false)); // false
console.log(isNil([])); // false
console.log(isNil({})); // false

It can also be used as a type guard in TypeScript:

typescript

function processValue(value: string | null | undefined) {
  if (isNil(value)) {
    // value is now narrowed to null | undefined
    console.log('Value is empty');
  } else {
    // value is narrowed to string
    console.log(value.toUpperCase());
  }
}

Parameters

value (unknown): The value to check if it's null or undefined.

Returns

(value is null | undefined): Returns true if the value is null or undefined, false otherwise.