$('#form_meta_edit').attr('onsubmit', 'add_meta()');
<form id="form_meta_edit" onsubmit="bla_bla()"></form> <script src="http://code.jquery.com/jquery-latest.min.js"></script> <script> alert($('#form_meta_edit').attr('onsubmit')); $('#form_meta_edit').attr('onsubmit', 'add_meta()'); alert($('#form_meta_edit').attr('onsubmit')); </script>