Q1225 How can I start and stop the animation of an animated gif?

<img name="myAnim" src="running.gif" width=200 height=100 alt="Animation">

<form>
<input type="button" onClick="if (document.images) document.images['myAnim'].src='stopped.gif' value="stop">
<input type="button" onClick="if (document.images) document.images['myAnim'].src='running.gif?'+random() value="start">
</form>