Regexp-Toolkit : Build Custom Regular Expressions with Ease

npm version license typescript

Core Features

Index

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" user@example.com

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", "test@example.com");
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", "test@example.com") → 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.

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