<div id="one">One</div>
<div id="two">Two</div>
<p>Click one div, then while it's fading, click the other. The second div's animation will stop as soon as the first one's animation completes.</p>
CSS
div {
margin: 10px;
float: left;
width: 100px;
height: 100px;
background: red;
}
p {
margin: 10px;
clear: both;
}