is-truthy-ts

A type predicate for truthy values

Install

1npm install is-truthy-ts

The problem

Often you want to filter out nullish values from an array, but typescript doesn't type the result correctly by default:

1const arrayWithNulls = [1, 2, null, 4];
2
3const filtered = arrayWithNulls.filter(Boolean);
4// ❌ The type of filtered is (number | null)[]

Solution

1import { isTruthy } from 'is-truthy-ts';
2
3const arrayWithNulls = [1, 2, null, 4];
4const filtered = arrayWithNulls.filter(Boolean);
5// ✅ The type of filtered is number[]