作为一个马上要找工作、非计算机专业、热爱前端的大四狗，最近开始疯狂写demo、看书，准备九、十月份的校招。
晚上用js实现了一个比较简单（low）的拖拽效果，初步测试兼容性还是不错的，于是写一段小博文记录下~大神求轻喷
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
#box {
width: 100px;
height: 100px;
background: red;
position: absolute;
}
</style>
</head>
<body>
<div id="box"></div>
<script>
window.onload = function (){
var disX = 0;
var disY = 0;
var oBox = document.getElementById("box");
oBox.onmousedown = function (ev){
var oEvent = ev || event;
oBox.style.cursor = "move";
disX = oEvent.clientX - oBox.offsetLeft;
disY = oEvent.clientY - oBox.offsetTop;
document.onmousemove = function (ev){
var oEvent = ev || event;
var theLeft = oEvent.clientX - disX;
var theTop = oEvent.clientY - disY;
// 禁止用户从浏览器左框拖出
if (theLeft < 0) {
theLeft = 0;
} else if (theLeft > document.documentElement.clientWidth-
oBox.offsetWidth) {
theLeft = document.documentElement.clientWidth-
oBox.offsetWidth;
} else if (theTop < 0) {
theTop = 0;
} else if (theTop > document.documentElement.clientHeight-
oBox.offsetHeight) {
theTop = document.documentElement.clientHeight-
oBox.offsetHeight;
}
oBox.style.left = theLeft + ‘px‘;
oBox.style.top = theTop + ‘px‘;
}
}
document.onmouseup = function (){
document.onmousemove =null;
}
// 窗口重设大小时的处理方法
window.onresize = function (){
oBox.style.left = document.documentElement.clientWidth/2-oBox.offsetWidth/2 + ‘px‘;
oBox.style.top = document.documentElement.clientHeight/2-oBox.offsetHeight/2 + ‘px‘;
}
// 兼容firefox 3.6.19
return false;
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/zhongshanblog/p/4652785.html