【slidetoggle】
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-2.1.0.js'></script>
<style type='text/css'>
#show {
display: none;
margin-top: 20px;
}
</style>
<script type='text/javascript'>
$(window).load(function(){
$(document).on("click", "#clickme", function() {
$("#show").slideToggle();
});
});
</script>
</head>
<body>
<input type="button" id="clickme" value="Clickhere">
<div id="show">
<a>Hello</a>
</div>
</body>
</html>
