1、点击开始运动，盒子开始运动，碰到/超出可是区范围，盒子返回来运动。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>碰撞运动</title>
<style>
#div1{
width: 260px;
height: 160px;
background: url(pz.jpg) center center / cover no-repeat;
position: absolute;
left: 130px;
}
</style>
<script>
var iSpeedX=5;
var iSpeedY=6;
var timer=null;
window.onload=function(){
var oDiv=document.getElementById("div1");
var oBtn=document.getElementById("btn");
oBtn.onclick=function(){
startMove(oDiv);
}
}
function startMove(obj){
clearInterval(timer);
timer=setInterval(function(){
var l=obj.offsetLeft+iSpeedX;
var t=obj.offsetTop+iSpeedY;
if (l>document.documentElement.clientWidth-obj.offsetWidth) {
iSpeedX*=-1;
l=document.documentElement.clientWidth-obj.offsetWidth;
}
else if(l<0){
iSpeedX*=-1;
}
if (t>document.documentElement.clientHeight-obj.offsetHeight) {
iSpeedY*=-1;
t=document.documentElement.clientHeight-obj.offsetHeight;
}
else if(t<0){
iSpeedY*=-1;
}
obj.style.left=l+'px';
obj.style.top=t+'px';
},30);
}
</script>
</head>
<body>
<div id="div1"></div>
<input type="button" value="点击开始运动" id="btn">
</body>
</html>结果展示：
