1<style>
2    div {
3        width: 50px;
4        height: 50px;
5        background-color: green;
6    }
7
8    div.square {
9        width: 100px;
10        height: 100px;
11        -webkit-transition-property: height;
12        -webkit-transition-duration: 2s;
13    }
14    
15    div.rectangle {
16        width: 100px;
17        height: 200px;
18        -webkit-transition-property: width, height;
19        -webkit-transition-duration: 5s;
20    }
21</style>
22<p id="instructions">
23    When you click the Change button, the shape will
24    <span id="description"></span>.
25    <button style="display: block;" onclick="transition()">Change</button>
26</p>
27<div id="target"></div>
28<script>
29    var state = 0;
30    var transitions = [
31        {className:"rectangle", description:"animate to a large rectangle over 5 seconds."},
32        {className:"square", description:"animate to a square over 2 seconds.  Try clicking before the first animation finishes and make sure the width doesn't do an ugly jump."},
33        {className:"", description:"instantly change to a small square"},
34        {className:"square", description:"instantly change into a small rectangle and then animate into a large square over 2 seconds"},
35        {className:"rectangle", description:"animate to a large rectangle over 5 seconds"},
36        {className:"", description:"instantly change to a small square"}
37    ];
38
39    document.getElementById("description").innerText = transitions[0].description;
40
41    function transition()
42    {
43        var target = document.getElementById("target");
44        target.className = transitions[state].className;
45        state++;
46        if (state < transitions.length)
47            document.getElementById("description").innerText = transitions[state].description;
48        else {
49            document.getElementById("instructions").innerText = "Done.";
50        }
51    }
52</script>
53