regkata

Master regular expressions through practice, one kata at a time.

An interactive CLI tool that teaches you regex the way martial artists learn moves—through deliberate practice and progressive challenges. Inspired by vimtutor, regkata guides you from regex basics to advanced patterns with hands-on lessons.

Why regkata?

Regular expressions are powerful but intimidating. Most tutorials throw syntax at you and hope it sticks. regkata takes a different approach: learn by doing. Each lesson presents a challenge, you write the regex, and get instant feedback. No copy-paste, no passive reading—just you and the pattern.

Features

• ✨ 22 Progressive Lessons - From fundamentals to real-world applications
• 🥋 Belt System - White Belt (core patterns) → Yellow Belt (practical challenges)
• 🎯 Real-time Validation - Test your regex against multiple cases instantly
• 💾 Progress Tracking - Pick up exactly where you left off
• 💡 Hint System - Stuck? Type ? for guidance
• 🎨 Beautiful CLI - Clean, colorful interface built with React
• ⚡ Lightning Fast - Powered by Bun for instant startup

Installation

Install globally with Bun:

bun install -g regkata

Or with npm:

npm install -g regkata

Usage

Start your training:

regkata

Controls

• Arrow keys - Navigate menu options
• Enter - Submit your regex or select a lesson
• ? - Show hint for the current lesson
• exit - Return to menu

Learning Path

Your progress is automatically saved. When you return:

• ✓ Completed lessons are marked
• Resume from where you left off
• Or jump to any lesson to review

What You'll Learn

⬜ White Belt - Fundamentals

Master the core regex patterns and syntax

Lesson  1: Literal Characters         →  Match exact text
Lesson  2: The Dot Metacharacter      →  Match any character
Lesson  3: Character Classes          →  Match sets of characters
Lesson  4: Character Ranges           →  Match ranges like [0-9]
Lesson  5: Negated Character Classes  →  Match anything BUT these
Lesson  6: Shorthand Character Classes →  \w, \d, \s shortcuts
Lesson  7: The Plus Quantifier        →  Match one or more
Lesson  8: The Star Quantifier        →  Match zero or more
Lesson  9: The Question Mark          →  Make optional
Lesson 10: Anchors - Start            →  ^ matches string start
Lesson 11: Anchors - End              →  $ matches string end
Lesson 12: Word Boundaries            →  \b matches word edges
Lesson 13: Alternation                →  Match this OR that
Lesson 14: Grouping                   →  Combine patterns
Lesson 15: Escaping Special Chars     →  Match literal . ? * etc.

🟨 Yellow Belt - Real World

Apply regex to practical challenges and data extraction

Lesson 16: Extract IPv4 Addresses     →  Parse server logs
Lesson 17: Extract Email Addresses    →  Find emails in text
Lesson 18: Extract URLs               →  Match HTTP/HTTPS links
Lesson 19: Parse Dates                →  MM/DD/YYYY format
Lesson 20: Extract Phone Numbers      →  US XXX-XXX-XXXX format
Lesson 21: Extract Hashtags           →  Social media tags
Lesson 22: Parse Hex Colors           →  #RGB and #RRGGBB

Development

Clone and install dependencies:

git clone https://github.com/JR-G/regkata.git
cd regkata
bun install

Run in development mode:

bun run dev

Type checking:

bun run typecheck

Build for production:

bun run build

License

MIT © James Glenn