$(document).on('click', '#ajax_form_submit', function(){ $('#ajaxForm').ajaxSubmit({ beforeSubmit: function(a,f,o) { o.dataType = 'script'; if (o.dataType == 'script') { o.url = o.url.split('?'); // split on GET params if (o.url[0].substr(-3) != '.js') o.url[0] += '.js'; // force rails to respond to respond to the request with :format = js o.url = o.url.join('?'); // join on GET params alert(o.url) } } }); });