触壁反弹

来源：互联网发布：json格式错误怎么办编辑：程序博客网时间：2024/04/28 12:30

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
padding: 0;
margin: 0;
}
#wrap{
position: relative;
width: 500px;
height: 400px;
border: solid 1px black;
}
#ball{
position: absolute;
width: 50px;
height: 50px;
border-radius: 50%;
background: pink;
}
</style>
</head>
<body>
<div id="wrap">
<div id="ball"></div>
</div>
</body>
<script type="text/javascript">
var wrap = document.getElementById("wrap");
var ball = document.getElementById("ball");
//x控制的是小球的left值
var x = 0;
//控制小球的top值
var y = 0;
var speedX = 10;
var speedY = 20;
setInterval(function(){
//通过left属性在改变水平方向的运动
x = x + speedX;
if(x >= 450){
speedX = speedX * (-1);
}else if(x <= 0){
speedX = speedX * (-1);
}
ball.style.left = x + 'px';
//通过top属性来改变竖直方向的运动
y = y + speedY;
if(y >= 350){
speedY = speedY * (-1);
}else if(y <= 0){
speedY = speedY * (-1);
}
ball.style.top = y + 'px';
},50)
</script>
</html>

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