JQ控制点击隐藏和出现下来列表

http://www.w3school.com.cn/tiy/t.asp?f=jquery_effect_toggle

<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$(".btn1").click(function(){
$("p").toggle();
});
});
</script>
</head>
<body>
<p>This is a paragraph.</p>
<button class="btn1">Toggle</button>
</body>
</html>