<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>拖拽div</title>
<style type="text/css">
#box1{
width: 60px;
height: 60px;
background-color: green;
position: absolute;
}
#box2{
width: 1890px;
height: 860px;
background-color: pink;
}
</style>
<script type="text/javascript">
window.onload=function(){
var box1=document.getElementById("box1");
//1.鼠标按下，onmousedown
box1.onmousedown=function(event){
//div的偏移量：鼠标.clientX-元素.offsetLeft
//div的偏移量：鼠标.clientY-元素.offsetTop
var ol=event.clientX-box1.offsetLeft;
var ot=event.clientY-box1.offsetTop;
event=event||window.event;
//2.拖拽，onmousemove
document.onmousemove=function(event){
event=event||window.event;
var left=event.clientX-ol;
var top=event.clientY-ot;
box1.style.left=left+"px";
box1.style.top=top+"px";
};
//3.鼠标松开，onmouseup
document.onmouseup=function(){
document.onmousemove=null;
document.onmouseup=null;
};
return false;//取消浏览器默认行为，IE8及以下版本不兼容
};
}
</script>
</head>
<body>
<div id="box1"></div>
<div id="box2"></div>
</body>
</html>
(作者观看的学习视频：B站尚硅谷）
