JavaScript: The game logic is implemented in JavaScript, handling everything from piece movement to game rules and state management. I used an object-oriented approach to model the chess pieces, their positions, and interactions. Event listeners detect user actions, validating legal moves and updating the board accordingly. Special rules like castling, en passant, and pawn promotion are also included to ensure a complete gameplay experience. Additionally, JavaScript manages the UI updates, such as highlighting possible moves and providing feedback for illegal moves.