♟️ JS Chess Engine

A lightweight, fully functional Chess game built from scratch using HTML, CSS, and Vanilla JavaScript. It features a custom AI opponent that uses the Minimax algorithm with Alpha-Beta pruning to calculate moves.

🚀 Live Demo

Click here to play the game

✨ Features

• Game Modes:
  • Player vs Player: Classic hot-seat multiplayer.
  • Player vs Computer: Challenge the AI engine.
• Smart AI:
  • Easy: Makes random moves (good for testing).
  • Medium: Looks 2 moves ahead.
  • Hard: Looks 3 moves ahead and uses advanced positional evaluation.
• Color Selection: Choose to play as White or Black (AI automatically rotates the board).
• Performance: Uses Web Workers to run the AI calculations in a background thread, ensuring the UI never freezes or lags while the computer thinks.
• Game Logic: Full move validation (check, checkmate, stalemate, castling, promotion) powered by chess.js.

🛠️ Tech Stack

• Frontend: HTML5, CSS3 (Grid Layout).
• Logic: Vanilla JavaScript (ES6+).
• Multithreading: Web API (Web Workers).
• Library: Chess.js (for move generation and validation).

🧠 How the AI Works

The computer player is built on a Minimax Algorithm with Alpha-Beta Pruning to optimize performance. It evaluates the board based on:

1. Material Score: Values pieces (Pawn=10, Queen=90, etc.) to calculate who has the material advantage.
2. Positional Strategy:
   • Center Control: Bonus points for controlling the center squares (d4, e4, d5, e5).
   • Pawn Structure: Incentivizes advancing pawns closer to promotion.
   • Development: Penalties for leaving Knights and Bishops on the back rank too long.
3. Randomness: Adds slight "noise" to evaluations to ensure the AI plays varied moves rather than the same game every time.

📂 Project Structure

├── index.html      # Main game interface and DOM structure
├── style.css       # Styling, Grid board, and animations
├── script.js       # UI logic, Game loop, and Event listeners
└── worker.js       # The "Brain" - AI logic running in a separate thread

📦 How to Run Locally

Since this project uses standard web technologies, you don't need to install any dependencies (like Node.js).

1. Clone the repository:

git clone "https://github.com/dhruv-jani-0808/Chess-Game-using-alpha-beta-AI-algorithm"

2. Open the game: Simply double-click index.html to open it in your browser. Note: Some browsers block Web Workers when running from local files (file://). If the AI doesn't move, try running it through a local server (like VS Code's "Live Server" extension).

🤝 Contributing

Contributions are welcome!

• Found a bug or have an idea? Feel free to raise an issue. If you want to work on it, just let me know in the comments and I will assign it to you.
• Ready to code? You can also simply fork the repository and submit a Pull Request (PR) directly.