stringMatching

Matcher for a string matching a regular expression.

Matchers are applied through assertObjectMatches, where they narrow the corresponding property type.

A regular expression carries no type-level shape, so the property is narrowed to a string and no further.

Usage

import { assertObjectMatches, stringMatching } from "@kensio/smartass";

const value: unknown = {
  key: "2026/08/23/14/orders-1-2026-08-23-14-30-00-000",
};

assertObjectMatches(value, {
  key: stringMatching(/^\d{4}\/\d{2}\/\d{2}\//),
});

// value is now narrowed to an object with a string key
// {
//   key: string;
// }

Source

Source file: src/assert/string-matches/string-matches.match.ts