Regexp-Toolkit : Build Custom Regular Expressions with Ease

Core Features

• Chainable, easy-to-use API for building custom regex patterns.

• Built-in validators and character classes for common use cases.

• Clear and readable regex construction for better maintainability.

• Full customization with raw regex support.

• Works seamlessly in Node.js and browser environments.

• Includes a handy CLI for quick regex testing.

• Developed with TypeScript for type safety and better tooling.

• Compatible with both CommonJS and ES6 module systems.

Index

• Getting Started
• Import
• CLI Usage
• Examples
• Regexp Method - Beginner-Friendly API
  • Character Classes
  • Quantifiers
  • Anchors & Structure
  • Grouping & Logic
  • Output & Testing
• Built-in Validators
  • General Validators
  • Format & Pattern Validators
  • Date & Time Validators
  • Network Validators
• License
• Contributing
• Connect with Me

Getting Started

You can install the module via npm or yarn:

npm install regexp-toolkit

yarn add regexp-toolkit

Import

// Using ES6 imports
import { regex } from "regexp-toolkit";

// Using Node.js `require()`
const { regex } = require("regexp-toolkit");

CLI Usage

regexp-toolkit includes a handy CLI tool for quick testing of regex patterns directly from the terminal.

Test a Regex Pattern

npx regex-tester "email" [email protected]

Examples

Example 1:

import { regex } from "regexp-toolkit";

const pattern = regex().digit().oneOrMore().toRegex();
console.log(pattern.test("12345")); // true
console.log(pattern.test("abc")); // false

Example 2

import { validate } from "regexp-toolkit";

const isValidEmail = validate("email", "[email protected]");
console.log(isValidEmail); // true

Regexp Method - Beginner-Friendly API

Character Classes

| Method | Usage | Example | | -------------------- | ----------------------------------------- | --------------------------------------------------------------------------------------- | | digit() | Matches any digit from 0 to 9 | regex().digit() on "123" → matches ["1", "2", "3"] | | letter() | Matches any uppercase or lowercase letter | regex().letter() on "aB1" → matches ["a", "B"] | | lowercase() | Matches lowercase letters only | regex().lowercase() on "abAB" → matches ["a", "b"] | | uppercase() | Matches uppercase letters only | regex().uppercase() on "abAB" → matches ["A", "B"] | | lettersOrNumbers() | Matches any letter or digit | regex().lettersOrNumbers() on "abc123$%" → matches ["a", "b", "c", "1", "2", "3"] | | whitespace() | Matches spaces, tabs, newlines | regex().whitespace() on "a b\tc\n" → matches [" ", "\t", "\n"] | | nonWhitespace() | Matches any non-space character | regex().nonWhitespace() on "a b" → matches ["a", "b"] | | wordChar() | Matches letters, numbers, or underscore | regex().wordChar() on "a_1!" → matches ["a", "_", "1"] | | nonWordChar() | Matches non-word characters | regex().nonWordChar() on "a_1!" → matches ["!"] | | anyChar() | Matches any single character | regex().anyChar() on "abc" → matches ["a", "b", "c"] | | custom("abc") | Matches specific characters | regex().custom("abc") on "abcd" → matches ["a", "b", "c"] |

Quantifiers

| Method | Usage | Example | | --------------- | -------------------------- | ----------------------------------------------------------------- | | one() | Matches exactly once | regex().digit().one() on "123" → matches "1" | | zeroOrMore() | Matches zero or more times | regex().digit().zeroOrMore() on "abc123xyz" → matches "123" | | oneOrMore() | Matches one or more times | regex().digit().oneOrMore() on "abc456" → matches "456" | | optional() | Matches once or not at all | regex().letter().optional() on "9a" → matches "a" | | between(2, 4) | Matches 2 to 4 times | regex().digit().between(2, 4) on "12345" → matches "1234" | | exactly(3) | Matches exactly 3 times | regex().digit().exactly(3) on "007" → matches "007" | | atLeast(5) | Matches 5 or more times | regex().digit().atLeast(5) on "1234567" → matches "1234567" |

Anchors & Structure

| Method | Usage | Example | | ---------- | --------------------------------- | ----------------------------------------------------- | | start() | Match must start at beginning | regex().start().letter() on "Abc" → matches "A" | | end() | Match must end at end | regex().digit().end() on "room5" → matches "5" | | strict() | Matches the entire string exactly | regex().digit().strict() on "3" → matches "3" |

Grouping & Logic

| Method | Usage | Example | | ------------------ | ------------------------------------------ | --------------------------------------------------------------------------- | | group(fn) | Groups part of the pattern (non-capturing) | regex().group(r => r.digit().oneOrMore()) on "123" → matches "123" | | capture(fn) | Captures part of the pattern | regex().capture(r => r.letter().exactly(2)) on "AB123" → matches "AB" | | or() | Matches one pattern or another | regex().digit().or().letter() on "3B" → matches ["3", "B"] | | then("abc") | Matches exact string | regex().then("abc") on "abc123" → matches "abc" | | raw("[A-Z]+") | Insert custom raw regex | regex().raw("[A-Z]+") on "GoUSA" → matches ["G", "USA"] | | not("abc") | Match if next part is NOT "abc" | regex().not("abc").then("def") on "def" → matches "def" | | lookahead("xyz") | Match only if followed by "xyz" | regex().letter().lookahead("xyz") on "Axyz" → matches "A" |

Output & Testing

| Method | Usage | Example | | --------------- | ----------------------------------------------------------- | ----------------------------------------------------------------- | | toRegex("g") | Returns RegExp object | regex().digit().toRegex("g") on "a1b2" → matches ["1", "2"] | | toString() | Returns regex string | regex().digit().toString() → "\\d" | | test(input) | Tests if the pattern matches input string (returns boolean) | regex().letter().test("abc") → true | | match("a1b2") | Finds matches in string | regex().digit().match("a1b2") → ["1", "2"] |

Built-in Validators

Use the validate function with the validator name and the value to check if it is valid.

General Validators

| Validator | Usage | Example | | --------- | -------------------------- | ----------------------------------------------------------------- | | email | validate("email", value) | validate("email", "[email protected]") → true | | phone | validate("phone", value) | validate("phone", "+12345678901") → true | | url | validate("url", value) | validate("url", "https://example.com") → true | | uuid | validate("uuid", value) | validate("uuid", "123e4567-e89b-12d3-a456-426614174000") → true |

Format & Pattern Validators

| Validator | Usage | Example | | ---------- | ----------------------------- | ----------------------------------------- | | username | validate("username", value) | validate("username", "user_123") → true | | password | validate("password", value) | validate("password", "abc123") → true | | slug | validate("slug", value) | validate("slug", "my-url-slug") → true | | hex | validate("hex", value) | validate("hex", "#ff0033") → true | | htmlTag | validate("htmlTag", value) | validate("htmlTag", "<div>") → true |

Date & Time Validators

| Validator | Usage | Example | | --------- | ------------------------- | --------------------------------------- | | date | validate("date", value) | validate("date", "2025-06-08") → true | | time | validate("time", value) | validate("time", "23:59") → true |

Network Validators

| Validator | Usage | Example | | --------- | ------------------------- | ---------------------------------------- | | ipv4 | validate("ipv4", value) | validate("ipv4", "192.168.0.1") → true |

License

This project is licensed under the MIT License. Feel free to use, modify, and distribute it freely.

Contributing

Contributions, issues, and feature requests are welcome!
Feel free to check the issues page or submit a pull request.

Connect with Me

• GitHub
• LinkedIn