GameEngine - Memory Card Game Module

A standalone, framework-free JavaScript module for memory card game logic.

Features

• Deck Creation: Automatically generates card pairs
• Shuffling: Fisher-Yates algorithm for random card placement
• Card Flipping: Handles flip logic with validation
• Matching Logic: Detects and tracks matched pairs
• Move Counting: Tracks player moves
• Game-Over Detection: Automatically detects when all pairs are matched

API

Constructor

const engine = new GameEngine();

Methods

start(pairCount = 8)

Initialize and start a new game.

• Parameters: pairCount - Number of card pairs (default: 8)
• Returns: Game state object

const state = engine.start(8); // Start with 8 pairs (16 cards)

flip(cardId)

Flip a card and handle matching logic.

• Parameters: cardId - Unique card identifier
• Returns: Updated game state object

const state = engine.flip('card-0-a');

getState()

Get current game state as plain JSON.

• Returns: Game state object

const state = engine.getState();

reset()

Reset the game to initial state.

• Returns: Initial game state object

const state = engine.reset();

resetFlippedCards()

Reset non-matched flipped cards (call after mismatch delay).

• Returns: Updated game state object

// After showing mismatch for 1 second
setTimeout(() => {
  const state = engine.resetFlippedCards();
}, 1000);

State Object Structure

{
  cards: [
    { id: 'card-0-a', value: 0, flipped: false, matched: false },
    // ...
  ],
  moves: 0,
  gameStarted: false,
  gameOver: false,
  flippedCount: 0,
  matchedPairs: 0,
  isMatching: false,
  isMismatched: false
}

Usage Example

const engine = new GameEngine();

// Start game
let state = engine.start(8);

// Flip first card
state = engine.flip('card-0-a');

// Flip second card
state = engine.flip('card-3-b');

// Check if they match
if (state.isMismatched) {
  // Wait then reset
  setTimeout(() => {
    state = engine.resetFlippedCards();
  }, 1000);
}

// Check game over
if (state.gameOver) {
  console.log(`Won in ${state.moves} moves!`);
}

// Reset game
state = engine.reset();

Demo

Open example.html in a browser to see a working demo.

Module Export

The module supports CommonJS exports:

// Node.js
const GameEngine = require('./GameEngine.js');

Or use directly in browser:

<script src="GameEngine.js"></script>