因为mouseover和mouseout经常一起写，所以出现了hover()
hover(function(){},function(){});第一个参数为鼠标移入运行的函数，第二个为鼠标离开运行的函数
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style type="text/css">
#demo{200px; height:300px;background-color: green;}
</style>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$(function() {
// $("#demo").mouseover(function(){
// $(this).css({"width":"400px","height":"600px","background-color":"yellow"});
// });
// $("#demo").mouseout(function(){
// $(this).css({"width":"200px","height":"300px","background-color":"green"});
// });
$("#demo").hover(function() {
$(this).css({"width":"400px","height":"600px","background-color":"yellow"});
}, function() {
$(this).css({"width":"200px","height":"300px","background-color":"green"});
});
});
//也可以使用简化的hover
/*一般用这个比较多，鼠标进入离开都执行这个函数。
$("ul").hover(function(){
$(".lei").toggle();
});
*/
</script>
</head>
<body>
<div id="demo"></div>
</body>
</html>