function previewContactSheet() {var url = 'contactsheet.php';var formdata = $('contactsheetform').serialize() + '&preview=true'; var ajax = new Ajax.Request(url,{method: 'get', parameters:formdata, onSuccess: function(response) {refreshIt();}});}function refreshIt() {   document.previewimage.src = 'filestore/tmp/contactsheet.jpg?'+ Math.random();}