jQuery Callback 函数. 首先隐藏文字，然后弹出对话框
<html>
<head>
<script type="text/javascript" src="jquery-1.7.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$("button").click(function(){
$("p").hide(1000,function(){
alert("The paragraph is now hidden");
});
});
});
</script>
</head>
<body>
<button type="button">Hide</button>
<p>This is a paragraph with little content.</p>
</body>
</html>