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Getting Started

Goal​

Regular expressions are a powerful tool for matching text patterns, yet they are notorious for their hard-to-parse syntax, especially in the case of more complex patterns.

This library allows users to create regular expressions in a structured way, making them easy to write and review. It provides a domain-specific language for defining regular expressions, which are finally turned into JavaScript-native RegExp objects for fast execution.

// Regular JS RegExp
const hexColor = /^#?([0-9a-fA-F]{6}|[0-9a-fA-F]{3})$/;

// TS Regex Builder DSL
const hexDigit = /[0-9a-fA-F]/; // or charClass(charRange('0', '9'), charRange('a', 'f'), charRange('A', 'F'));

const hexColor = buildRegExp([
  startOfString,
  optional('#'),
  capture(
    choiceOf(
      repeat(hexDigit, 6), // #rrggbb
      repeat(hexDigit, 3), // #rgb
    ),
  ),
  endOfString,
]);

Installation​

npm install ts-regex-builder

Basic usage​

import { buildRegExp, capture, oneOrMore } from 'ts-regex-builder';

// /Hello (\w+)/
const regex = buildRegExp(['Hello ', capture(oneOrMore(word))]);

Performance​

Regular expressions created with this library are executed at runtime, so you should avoid creating them in a context where they would need to be executed multiple times, e.g., inside loops or functions. We recommend that you create a top-level object for each required regex.

License​

MIT

Inspiration​

TS Regex Builder is inspired by Swift Regex Builder API.