[Zvona]

You can also use syntax (works on IE & Moz) :
oObject.onEvent = sFunction;

an example :

<script type="text/javascript">
<!--
var myImage = new Image();
var myImage2 = new Image();

myImage.onclick = zAlert;
myImage2.onmouseover = zOver;

function zOver(e)
{
 alert("Never hover my images anymore!");
}

function zAlert(e)
{
 alert("How dare you to click my images?!?");
}
// -->