throws

A Typescript assertion that throws only throws on null and undefined. Typically when writing code we only want to throw on those conditions. Traditional assert or invariant functions throw on all falsy values, and can easily trip you up when you accidentally pass in a valid number that is 0.

Installation

pnpm add throws

... or the equivalent for your package manager.

Usage

import { throws } from "throws";

const valueOrUndefined: number | undefined = 0;

throws(valueOrUndefined, "This is a required value");

/**
 * At this point Typescript will know that valueOrUndefined is not undefined and
 * will allow you to continue writing safe code.
 */

No Unchecked Indexed Access

If you are using the recommended strict noUncheckedIndexedAccess setting, you might want to check out get-or-throw.