<html>
<head>
<script src="https://libs.baidu.com/jquery/1.10.2/jquery.min.js">
</script>
<script>
$(document).ready(function()
{
$("#btn1").click(function(){
$("#box").animate({height:"300px"});
});
$("#btn2").click(function(){
$("#box").animate({height:"100px"});
});
});
</script>
</head>
<body>
<button id="btn1">Animate height</button>
<button id="btn2">Reset height</button>
<div id="box" style="background:#98bf21;height:100px;width:100px;margin:6px;">
</div>
</body>
</html>