♟️ Classic Chess JS

A complete chess game built with vanilla JavaScript. Play against a friend or challenge the AI with three difficulty levels - perfect for both casual players and chess enthusiasts!

🌐 Live Demo

📂 File Structure

classic-chess-js/
├── pieces/               # All chess piece images
│   ├── white_pawn.png
│   ├── black_king.png
│   └── ... (12 total)
├── assets/               # Additional assets
│   └── screenshot.png    # Game preview
├── index.html           # Main game interface
├── styles.css           # All visual styling
├── script.js            # Game logic (2000+ lines)
├── README.md            # This document
└── LICENSE              # MIT License

🎮 Features

Game Modes:

• 👥 Local 2-player
• 🤖 AI opponent (Easy/Medium/Hard)

Full Chess Rules:

• ♜ Castling (both kingside and queenside)
• ♟ En passant captures
• ♛ Pawn promotion
• ⚔️ Check/checkmate detection
• 🏳️ Stalemate recognition

Player Tools:

• 💡 Smart move hints
• ↩️ Unlimited undo
• ⏱️ Adjustable timers (3/5/10/15 min)
• 🔄 Instant restart

🚀 Quick Start

1. Download the game

   git clone https://github.com/sagarbudhwani/classic-chess-js.git
   

2. Open in browser

   • Simply double-click index.html
   • Works in Chrome, Firefox, Edge (no server needed)

3. Start playing!

   • Choose game mode and settings
   • Drag pieces or click to move

🤖 AI Difficulty Explained

Level	Algorithm	Speed	Skill
Easy	Random valid moves	Instant	Beginner
Medium	1-ply greedy search	Fast	Intermediate
Hard	3-ply minimax	1-2 sec delay	Advanced

// Sample AI evaluation (from script.js)
function evaluatePosition() {
  // Values pieces: pawn=1, knight/bishop=3, rook=5, queen=9
  // Considers: king safety, piece activity, pawn structure
}

🛠️ Development Highlights

Tricky Parts I Solved:

1. Castling Logic
   Had to track if king/rook moved while ensuring no squares are under attack

2. En Passant
   Implemented special state tracking after pawn double-moves

3. Check Detection
   Optimized by checking attack paths to king instead of full board scan

You Might Notice:

• The AI pauses slightly on Hard difficulty (better simulation!)
• Mobile touch works but desktop is smoother
• Promotion always goes to queen (simpler UI)

🌟 Tips for Players

1. Use hints when learning (lightbulb button)
2. Right-click cancels piece selection
3. Enable timer for tournament-style games

📜 License

MIT © Sagar Budhwani - Free to use, modify, and share! See LICENSE.