<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
#box{width: 200px;height: 200px;background-color: red;position: absolute;}
</style>
<script>
window.onload = function(){
var Div = document.getElementById("box");
Div.onmousedown = function(ev){
var e = ev || window.event;
offsetX = e.clientX - Div.offsetLeft;
offsetY = e.clientY - Div.offsetTop;
}
document.onmousemove = function(ev){
var e = ev || window.event;
Div.style.left = e.clientX - offsetX + "px";
Div.style.top = e.clientY - offsetY + "px";
}
Div.onmouseup = function(e){
document.onmousemove = null;
}
}
</script>
</head>
<body>
<div id="box"></div>
</body>
</html>
我知道把
document.onmousemove = function(ev){
var e = ev || window.event;
Div.style.left = e.clientX - offsetX + "px";
Div.style.top = e.clientY - offsetY + "px";
}
这段代码放到Div.onmousedown = function(ev)里面就对了，
但是为什么我这样写是错的？
