matchesPattern

matchesPattern is a general purpose validator for validating values against arbitrary regex patterns.

import { matchesPattern } from 'revalidate';

const isAlphabetic = matchesPattern(/^[A-Za-z]+$/)('Username');

isAlphabetic('abc'); // undefined, so valid
isAlphabetic('123'); // 'Username must match pattern /^[A-Za-z]+$/'

Note: matchesPattern does not require a value, so falsy values will pass.

isAlphabetic();      // undefined because not required, so valid
isAlphabetic(null);  // undefined because not required, so valid
isAlphabetic('');    // undefined because not required, so valid