JavaScript实现鼠标拖动元素位置互换

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <body> <style type="text/css"> div.box{ position:relative; padding:5px; background-color:#000; width:300px; height:300px; overflow:hidden; } div.box div.item{ float:left; width:90px; height:90px; background-color:#ccc; margin:5px; position:relative; cursor:pointer; } div.mask{     width:90px;     height:90px;     background-color:#f00;     opacity:0.8;     filter:progid:DXImageTransform.Microsoft.Alpha(opacity=80);     position:absolute;     visibility:hidden;     top:20px;     left:20px;     z-index:10; } </style>  </body> </html> 

[Ctrl+A 全选 注:引入外部Js需再刷新一下页面才能执行]