<script language=javascript>
function test()
{
        document.getElementById("bbb").innerHTML="ooooooooooooooooooooooooooooooooooooo";
}
</script>
 
hadfjashfksdf<br />
sdjslfjdsl<br />
sjdksjadhask<br />
hjfskdjfh<br />
dfsjkdfhdsf<br />
<div id="bbb">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</div>
sjfsakdjflsa<br />
 
hsdkjhsd<br />
<input type=button onClick="test()" value=testen/>