<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>碰撞+重力运动</title> <style> #div1 { width:100px; height:100px; background:red; position:absolute; } </style> <script type="text/javascript"> window.onload = function(){ var oBtn = document.getElementById("btn"); oBtn.onclick = function(){ move(); } } //碰撞+重力 运动（计算空气阻力） var timer = null; //横向初速度 var speedX = 6; //竖向初速度速度 var speedY = 8; function move(){ clearInterval(timer); timer = setInterval(function(){ var oDiv = document.getElementById("div1"); //类似重力加速度 : g = 3; //竖向加速度:3 speedY+=3; var l = oDiv.offsetLeft + speedX ; var t = oDiv.offsetTop + speedY; if(t >= document.documentElement.clientHeight-oDiv.offsetHeight) { //竖向空气阻力 speedY*=-0.8; //横向空气阻力 speedX*=0.8; //将top设置为(document.documentElement.clientHeight - oDiv.offsetHeight)px t = document.documentElement.clientHeight - oDiv.offsetHeight; } else if(t<=0) { //竖向空气阻力 speedY*=-0.8; //横向空气阻力 speedX*=0.8; //将top设置为0px t=0; } if(l>=document.documentElement.clientWidth-oDiv.offsetWidth) { //横向空气阻力 speedX*=-0.8; //将left设置为(document.documentElement.clientWidth - oDiv.offsetWidth)px l = document.documentElement.clientWidth - oDiv.offsetWidth; } else if(l<=0) { //横向空气阻力 speedX*=-0.8; //将left设置为0px l = 0; } //将横向速度设置为0 if(Math.abs(speedX)<1) { speedX = 0; } //将竖向速度设置为0 if(Math.abs(speedY)<1) { speedY = 0; } //关闭定时器 //横、竖速度都为空及物体距顶部高度为(可视窗口高度 - 物体高度) if(speedX==0 && speedY==0 && t==document.documentElement.clientHeight-oDiv.offsetHeight) { clearInterval(timer); } else { oDiv.style.left = l+'px'; oDiv.style.top = t +'px'; } },30); } </script> </head> <body> <input type="button" id="btn" value="运动" /> <div id="div1"> </div> <span style="1px;height:300px;background:black;left:300px"></span> </body> </html>