jQuery简单拖拽原理实现，很不错收藏了
[code lang=”html”]
<!DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>简单拖曵原理实例</title>
<style type="text/css">
#drag{width:400px;height:300px;background:url(http://upload.yxgz.cn/uploadfile/2009/0513/20090513052611873.jpg);cursor:move;position:absolute;top:100px;left:100px;border:solid 1px #ccc;}
h2{color:#fff;background: none repeat scroll 0 0 rgba(16, 90, 31, 0.7);color:#FFFFFF;height:40px;line-height:40px;margin:0;}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(function(){
/*————–拖曳效果—————-
*原理：标记拖曳状态dragging ,坐标位置iX, iY
* mousedown:fn(){dragging = true, 记录起始坐标位置，设置鼠标捕获}
* mouseover:fn(){判断如果dragging = true, 则当前坐标位置 – 记录起始坐标位置，绝对定位的元素获得差值}
* mouseup:fn(){dragging = false, 释放鼠标捕获，防止冒泡}
*/
var dragging = false;
var iX, iY;
$("#drag").mousedown(function(e) {
dragging = true;
iX = e.clientX – this.offsetLeft;
iY = e.clientY – this.offsetTop;
this.setCapture && this.setCapture();
return false;
});
document.onmousemove = function(e) {//拖动的时候，鼠标跟随
if (dragging) {
var e = e || window.event;
var oX = e.clientX – iX;
var oY = e.clientY – iY;
$("#drag").css({"left":oX + "px", "top":oY + "px"});
return false;
}
};
$(document).mouseup(function(e) {
dragging = false;
$("#drag")[0].releaseCapture();
e.cancelBubble = true;
})
})
</script>
</head>
<body>
<div id="drag">
<h2>来拖动我啊</h2>
</div>
</body>
</html>
[/code]
预览效果：http://www.ostools.net/jsbin/jgvzgkxl/1/edit#preview