isString

Problem

You need to narrow an unknown value to string — for example validating a query parameter or discriminating a union type.

Solution

Use isString(value) to narrow to string.

import { isString } from '@vielzeug/arsenal';

isString('hello'); // true
isString(42); // false
isString(null); // false

const values: unknown[] = ['a', 1, 'b', null, 'c'];
values.filter(isString); // ['a', 'b', 'c']

Related

• isNumber
• isPrimitive