is-not-null-or-undefined

A TypeScript utility function & type-guard to check if a value is not null or undefined.

Installation

npm

npm install is-not-null-or-undefined

yarn

yarn add is-not-null-or-undefined

pnpm

pnpm add is-not-null-or-undefined

Usage

import { isNotNullOrUndefined } from 'is-not-null-or-undefined';

// Returns true for non-`null` and non-`undefined` values
isNotNullOrUndefined('string'); // true
isNotNullOrUndefined(123); // true
isNotNullOrUndefined({}); // true
isNotNullOrUndefined([]); // true
isNotNullOrUndefined(false); // true
isNotNullOrUndefined(0); // true

// Returns false for `null` and `undefined` values
isNotNullOrUndefined(null); // false
isNotNullOrUndefined(undefined); // false

Type Guard

The function acts as a TypeScript type guard, narrowing the type from T | null | undefined to T:

const value: string | null | undefined = getValue();

if (isNotNullOrUndefined(value)) {
  // value is now typed as string
  console.log(value.toUpperCase());
}