实代码如下
<!DOCTYPE html><html><head> <meta charset="UTF-8"> <title></title> <style> .myDiv{width: 300px;height: 200px;border: 1px solid rgba(0,0,0,0.2);margin: 50px ;position: relative; } .topLine{width: 0px;height: 1px;background: black;position:absolute;left: 0;top: -1px; } .bottomLine{width: 0px;height: 1px;background: black;position:absolute;left: 0;bottom: -1px; } .leftLine{width: 1px;height: 0px;background: black;position:absolute;left: -1;bottom: -1px; } .rightLine{width: 1px;height: 0px;background: black;position:absolute;right: -1px;top: -1px; } </style></head><body> <div class="myDiv"> <div class="topLine"></div> <div class="rightLine"></div> <div class="bottomLine"></div> <div class="leftLine"></div> </div> <div class="myDiv"> <div class="topLine"></div> <div class="rightLine"></div> <div class="bottomLine"></div> <div class="leftLine"></div> </div> <script type="text/javascript" src="http://libs.baidu.com/jquery/2.0.0/jquery.js"></script> <script> $(function(){$(".myDiv").mouseover(function(){$(this).find(".topLine,.bottomLine").stop().animate({"width":"300px"});$(this).find(".rightLine,.leftLine").stop().animate({"height":"200px"}); })$(".myDiv").mouseout(function(){$(this).find(".topLine,.bottomLine").stop().animate({"width":"0px"});$(this).find(".rightLine,.leftLine").stop().animate({"height":"0px"});}) }) </script></body></html>总结