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Snake game in pure Javascript.
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| <!doctype html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1"> | |
| <title>snake</title> | |
| <style type="text/css"> | |
| * { margin: 0; padding: 0; } | |
| html, body { height: 100%; overflow: hidden; background: #002f38; } | |
| canvas { | |
| position: absolute; | |
| top: 50%; | |
| left: 50%; | |
| transform: translate(-50%, -50%); | |
| background: #003a43 !important; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas id="canvas" width="700" height="500"></canvas> | |
| <script src="snake.js"></script> | |
| </body> | |
| </html> |
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| 'use strict'; | |
| let scoreAudio = new Audio('score.wav'); | |
| let deathAudio = new Audio('death.wav'); | |
| scoreAudio.volume = deathAudio.volume = .03; | |
| let started = false; | |
| let paused = true; | |
| let input = []; | |
| window.addEventListener('keydown', function(ev) { | |
| switch(ev.key) { | |
| case 'a': case 'h': case 'ArrowLeft': | |
| case 's': case 'j': case 'ArrowDown': | |
| case 'w': case 'k': case 'ArrowUp': | |
| case 'd': case 'l': case 'ArrowRight': | |
| case ' ': | |
| ev.preventDefault(); | |
| if(!started) { | |
| started = true; | |
| paused = false; | |
| } | |
| } | |
| switch(ev.key) { | |
| case 'a': case 'h': case 'ArrowLeft': input.push('left'); break; | |
| case 's': case 'j': case 'ArrowDown': input.push('down'); break; | |
| case 'w': case 'k': case 'ArrowUp': input.push('up'); break; | |
| case 'd': case 'l': case 'ArrowRight': input.push('right'); break; | |
| case ' ': | |
| paused = !paused; | |
| input = []; | |
| break; | |
| } | |
| }); | |
| function randomCoords() { | |
| return { | |
| x: Math.floor(Math.random() * 35), | |
| y: Math.floor(Math.random() * 25) | |
| } | |
| } | |
| let score = 1; | |
| let snake = { dir: null, body: [ randomCoords() ] }; | |
| let fruit; | |
| do { // make sure that the fruid doesn't spawn on top of the snake | |
| fruit = randomCoords(); | |
| } while(fruit.x === snake.body[0].x && fruit.y === snake.body[0].y); | |
| function lose() { | |
| paused = true; | |
| deathAudio.play(); // ignore the promise | |
| window.confirm(`Your score was ${score}!`); | |
| location.reload(); | |
| } | |
| function update() { | |
| // snake direction | |
| let dir = input.shift(); | |
| if(dir === 'up' && snake.dir !== 'down') snake.dir = dir; | |
| if(dir === 'down' && snake.dir !== 'up') snake.dir = dir; | |
| if(dir === 'left' && snake.dir !== 'right') snake.dir = dir; | |
| if(dir === 'right' && snake.dir !== 'left') snake.dir = dir; | |
| if(dir === 'up' || dir === 'down') { | |
| while(input[0] === 'up' || input[0] === 'down') input.shift(); | |
| } | |
| if(dir === 'left' || dir === 'right') { | |
| while(input[0] === 'left' || input[0] === 'right') input.shift(); | |
| } | |
| input.length = Math.min(1, input.length); | |
| // snake head | |
| let head = null; | |
| if(snake.dir === 'up') { | |
| head = { x: snake.body[0].x, y: (snake.body[0].y - 1 + 25) % 25 }; | |
| } else if(snake.dir === 'down') { | |
| head = { x: snake.body[0].x, y: (snake.body[0].y + 1 + 25) % 25 }; | |
| } else if(snake.dir === 'left') { | |
| head = { x: (snake.body[0].x - 1 + 35) % 35, y: snake.body[0].y }; | |
| } else if(snake.dir === 'right') { | |
| head = { x: (snake.body[0].x + 1 + 35) % 35, y: snake.body[0].y }; | |
| } | |
| // check collisions between the snake's head and body | |
| snake.body.forEach(function(part, _) { | |
| if(head.x === part.x && head.y === part.y) lose(); | |
| }); | |
| let body = [ head ]; | |
| if(head.x === fruit.x && head.y === fruit.y) { // snake ate the fruit: grow | |
| score = score + 1; | |
| snake.body.forEach(function(part, i) { | |
| body[i + 1] = part; | |
| }); | |
| snake.body = body; | |
| // make sure that the fruid doesn't spawn on top of the snake | |
| let ok = null; | |
| do { | |
| ok = true; | |
| fruit = randomCoords(); | |
| snake.body.forEach(function(part, _) { | |
| if(fruit.x === part.x && fruit.y === part.y) ok = false; | |
| }); | |
| } while(!ok); | |
| scoreAudio.play(); // ignore the promise | |
| } else { // walk normally | |
| snake.body.forEach(function(part, i) { | |
| body[i + 1] = part; | |
| }); | |
| body.pop(); | |
| snake.body = body; | |
| } | |
| } | |
| let canvas = document.getElementById('canvas'); | |
| let ctx = canvas.getContext('2d'); | |
| function draw() { | |
| ctx.clearRect(0, 0, canvas.width, canvas.height); | |
| // fruit | |
| ctx.fillStyle = '#e92e36'; | |
| ctx.fillRect(fruit.x * 20, fruit.y * 20, 20, 20); | |
| // snake | |
| ctx.fillStyle = '#008fcd'; | |
| snake.body.forEach(function(part, _) { | |
| ctx.fillRect(part.x * 20, part.y * 20, 20, 20); | |
| }); | |
| } | |
| draw(); // initial draw | |
| let t1 = performance.now(); | |
| function step(t2) { | |
| if(t2 - t1 > 100) { | |
| t1 = t2; | |
| if(!paused) update(); | |
| } | |
| draw(); | |
| window.requestAnimationFrame(step); | |
| } | |
| window.requestAnimationFrame(step); |
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