mirip2 lah..

<form id='myForm'>
<input type=button value='add' onclick="open(1)" />
<input type=button value='cetak' onclick="open(2)" />
<input type=hidden id='act' name='act' value='' />
</form>
<script>
function open(stat=1){
var selectorform = 'form#myForm';
if(stat==1) statAct='add';
if(stat==2) statAct='pdf';
$("#act").val( statAct);
var datax = $(selectorform).serialize();
url="open.php?"+datax;
window.location = url;.
}
</script>