代码如下：
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Canvas</title> <style type="text/css"> *{ margin: 0; padding: 0; } html, body{ height: 100%; } #myCanvas{ background-color: #87CEEB; } </style> </head> <body> <canvas>您的浏览器不支持Canvas元素</canvas> <script type="text/javascript"> var canvas = document.getElementById("myCanvas"); var context = canvas.getContext("2d"); var practicles = []; for (var i = 0; i < 500; i++) {//循环生成500粒 practicles.push({ x: Math.random()*(window.innerWidth), y: Math.random()*(window.innerHeight), vx: Math.random()-0.5, vy: Math.random()+0.5, size: Math.random()*3+1, color: "#FFF" }) } function timeUpdate(){ context.clearRect(0,0,window.innerWidth,window.innerHeight);//清除画布区域 var practicle; for (var i = 0; i < 500; i++) { var practicle = practicles[i]; practicle.x += practicles[i].vx; practicle.y += practicles[i].vy; if (practicle.x<0) {practicle.x=window.innerWidth} if (practicle.x>window.innerWidth) {practicle.x=0} if (practicle.y>window.innerHeight) {practicle.y=0} context.beginPath(); context.arc(practicle.x,practicle.y,practicle.size,0,Math.PI*2) context.closePath(); context.fillStyle = practicle.color; context.fill(); } } setInterval(timeUpdate,40); </script> </body> </html>