使用折叠特效（Fold Effect）显示一个 div。
<!doctype html><html lang="en"><head>
<meta charset="utf-8">
<title>.show() 演示</title>
<link rel="stylesheet" href="//code.jquery.com/ui/1.10.4/themes/smoothness/jquery-ui.css">
<style>
div {
display: none;
width: 100px;
height: 100px;
background: #ccc;
border: 1px solid #000;
}
</style>
<script src="//code.jquery.com/jquery-1.10.2.js"></script>
<script src="//code.jquery.com/ui/1.10.4/jquery-ui.js"></script></head><body>
<button>显示 div</button><div></div>
<script>$( "button" ).click(function() {
$( "div" ).show( "fold", 1000 );});</script>
</body></html>
