```html
Snake
Snake
Score: 0
High: 0
Arrow keys or WASD to move · Space to start/pause · R to restart
```
```typescript
type Cell = { x: number; y: number };
type Direction = { x: number; y: number };
const GRID = 20;
const CELL = 20;
const INITIAL_TICK_MS = 150;
const MIN_TICK_MS = 60;
const SPEEDUP_EVERY = 5; // apples
const SPEEDUP_DELTA = 10; // ms
class Game {
private canvas: HTMLCanvasElement;
private ctx: CanvasRenderingContext2D;
private scoreEl: HTMLElement;
private highEl: HTMLElement;
private snake: Cell[];
private dir: Direction;
private pendingDir: Direction | null;
private food: Cell;
private score: number;
private high: number;
private tickMs: number;
private alive: boolean;
private started: boolean;
private paused: boolean;
private tickId: number | null = null;
constructor(canvas: HTMLCanvasElement, scoreEl: HTMLElement, highEl: HTMLElement) {
this.canvas = canvas;
this.ctx = canvas.getContext('2d')!;
this.scoreEl = scoreEl;
this.highEl = highEl;
// Load high score from localStorage
const storedHigh = localStorage.getItem('snake.high');
this.high = storedHigh ? parseInt(storedHigh, 10) : 0;
this.updateHighDisplay();
this.restart();
}
start(): void {
if (this.started && this.paused) {
this.paused = false;
this.tick();
} else if (!this.started) {
this.started = true;
this.paused = false;
this.tick();
}
}
togglePause(): void {
if (!this.started || !this.alive) return;
this.paused = !this.paused;
if (!this.paused) {
this.tick();
}
}
restart(): void {
// Reset to initial state
this.snake = [
{ x: 10, y: 10 },
{ x: 9, y: 10 },
{ x: 8, y: 10 }
];
this.dir = { x: 1, y: 0 }; // Moving right
this.pendingDir = null;
this.score = 0;
this.tickMs = INITIAL_TICK_MS;
this.alive = true;
this.started = false;
this.paused = true;
this.updateScoreDisplay();
this.spawnFood();
this.draw();
}
private spawnFood(): void {
let valid = false;
let x: number, y: number;
while (!valid) {
x = Math.floor(Math.random() * GRID);
y = Math.floor(Math.random() * GRID);
valid = true;
for (const segment of this.snake) {
if (segment.x === x && segment.y === y) {
valid = false;
break;
}
}
}
this.food = { x, y };
}
private tick(): void {
if (this.tickId) {
window.clearTimeout(this.tickId);
}
if (this.paused || !this.alive) {
this.draw();
return;
}
// Apply pending direction
if (this.pendingDir) {
// Prevent reverse direction
if (this.pendingDir.x !== -this.dir.x || this.pendingDir.y !== -this.dir.y) {
this.dir = this.pendingDir;
}
this.pendingDir = null;
}
// Calculate new head position
const head = this.snake[0];
const newHead = { x: head.x + this.dir.x, y: head.y + this.dir.y };
// Check wall collision
if (newHead.x < 0 || newHead.x >= GRID || newHead.y < 0 || newHead.y >= GRID) {
this.gameOver();
return;
}
// Check self collision (excluding tail that will move)
for (let i = 0; i < this.snake.length - 1; i++) {
if (newHead.x === this.snake[i].x && newHead.y === this.snake[i].y) {
this.gameOver();
return;
}
}
// Move snake
this.snake.unshift(newHead);
// Check apple collision
if (newHead.x === this.food.x && newHead.y === this.food.y) {
this.score++;
this.updateScoreDisplay();
// Speed up if needed
if (this.score % SPEEDUP_EVERY === 0) {
this.tickMs = Math.max(MIN_TICK_MS, this.tickMs - SPEEDUP_DELTA);
}
this.spawnFood();
} else {
this.snake.pop();
}
this.draw();
// Schedule next tick
this.tickId = window.setTimeout(() => this.tick(), this.tickMs);
}
private gameOver(): void {
this.alive = false;
this.paused = true;
// Update high score
if (this.score > this.high) {
this.high = this.score;
localStorage.setItem('snake.high', this.high.toString());
this.updateHighDisplay();
}
this.draw();
}
private updateScoreDisplay(): void {
this.scoreEl.textContent = `Score: ${this.score}`;
}
private updateHighDisplay(): void {
this.highEl.textContent = `High: ${this.high}`;
}
private draw(): void {
// Clear canvas
this.ctx.fillStyle = '#000';
this.ctx.fillRect(0, 0, this.canvas.width, this.canvas.height);
// Draw apple
this.ctx.fillStyle = '#c0392b';
this.ctx.fillRect(this.food.x * CELL, this.food.y * CELL, CELL, CELL);
// Draw snake
for (let i = 0; i < this.snake.length; i++) {
const segment = this.snake[i];
this.ctx.fillStyle = i === 0 ? '#7ed957' : '#3aa635';
this.ctx.fillRect(segment.x * CELL, segment.y * CELL, CELL, CELL);
}
// Draw overlays
if (!this.started) {
this.drawOverlay('Press Space to start');
} else if (this.paused) {
this.drawOverlay('Paused');
} else if (!this.alive) {
this.drawOverlay('Game Over — press R to restart');
}
}
private drawOverlay(text: string): void {
this.ctx.fillStyle = '#fff';
this.ctx.font = '20px sans-serif';
this.ctx.textAlign = 'center';
this.ctx.textBaseline = 'middle';
this.ctx.fillText(text, this.canvas.width / 2, this.canvas.height / 2);
}
public setDirection(x: number, y: number): void {
if (this.paused || !this.started || !this.alive) return;
// Prevent reverse direction
if (x === -this.dir.x && y === -this.dir.y) return;
this.pendingDir = { x, y };
}
}
// Top-level setup
const canvas = document.getElementById('game') as HTMLCanvasElement;
const scoreEl = document.getElementById('score')!;
const highEl = document.getElementById('high')!;
const game = new Game(canvas, scoreEl, highEl);
// Keyboard handling
window.addEventListener('keydown', (e) => {
switch (e.key) {
case 'ArrowUp':
case 'w':
case 'W':
e.preventDefault();
game.setDirection(0, -1);
break;
case 'ArrowDown':
case 's':
case 'S':
e.preventDefault();
game.setDirection(0, 1);
break;
case 'ArrowLeft':
case 'a':
case 'A':
e.preventDefault();
game.setDirection(-1, 0);
break;
case 'ArrowRight':
case 'd':
case 'D':
e.preventDefault();
game.setDirection(1, 0);
break;
case ' ':
e.preventDefault();
if (!game.started) {
game.start();
} else {
game.togglePause();
}
break;
case 'r':
case 'R':
e.preventDefault();
game.restart();
break;
}
});
```