Edit in JSFiddle

<html>
    <head><title>animate height</title>
    </head>
<body>
    <button id="animate">Animate</button>
    <br />
    <div id="box">
    </div>
</body>
</html>
$(document).ready(function()
                  {
                      $("#animate").click(function()
                                          {
                                              $("#box").animate({
                                                  "height":"200px"
                                              },"slow");
                                          });
                  });
#box
    {
        background-color:Orange;
        height:100px;
        width:100px;
        margin-left:40px;
        margin-top:40px;
    }