@quentinadam/ensure

A simple function that asserts that a value is not undefined or null and returns the narrowed value.

Usage

import ensure from '@quentinadam/ensure';

const a = ensure(1); // doesn't throw

const b = ensure(undefined); // throws an AssertionError

ensure(undefined, 'message'); // throws an AssertionError with a custom error message

ensure(undefined, new Error('message')); // throws a custom Error

const value: string | undefined = 'hello';
const narrowedValue = ensure(value); // narrows the type of value to string;
value.toUpperCase(); // works