jQuery, combine form serialize data with other variables

We use following for  form data in post
  $("div.ajax_list form#" + formName).serialize();
to add  variables such as formName
 var data0 = $("div.ajax_list form" + formName).serializeArray();
data0.push({name: 'formName', value: formName});
Complete example code:
function submitUpdateForm(formName){
     var data0 = $("div.ajax_list form" + formName).serializeArray();
      data0.push({name: 'formName', value: formName});
        $.post('../../_ajaxParts/System/lut_termnew.php', data0, function(data) {
                formatJson(data, '#notice');
                submitFilterForm();
        });
}