It was JS error which caused $$epiforms to not load.

Please ensure you don't  have issue like this http://world.episerver.com/forum/developer-forum/Addons/Thread-Container/2016/2/episerver-forms-not-using-ajax-mode/

This is JS sample code to handle all client-side epiforms events in AlloyMVC

<script>

   if (typeof $$epiforms !== 'undefined') {

       $$epiforms(document).ready(function myfunction() {

           console.log('listen to event');

           $$epiforms(".EPiServerForms").on("formsNavigationNextStep formsNavigationPrevStep formsSetupCompleted formsReset formsStartSubmitting formsSubmitted formsSubmittedError formsNavigateToStep formsStepValidating", function (event, param1, param2) {

               console.log($(this).get(0), event);

           });

       });

   }

</script>

Listen for formsLoadExternalScripts and formsLoadExternalCss events

<script>

   if (typeof $$epiforms !== 'undefined') {

       console.log('listen to event');

       $$epiforms(".EPiServerForms").on("formsLoadExternalScripts formsLoadExternalCss", function (event, param1, param2) {

               console.log($(this).get(0), event);

           });

   }

</script>

For QuickSilver site, you should put the script before  @Html.RequiredClientResources("Footer")

the jQuery event object contains information about

• type: type of the event
• working form DOM element: the DOM element raises the event
• workingFormInfo: contains all meta information of current EPiServer Forms
• formData: in some submitting-related events, this property will contain the standard FormData object of the submission

These event are kind of notification-only, they don't support cancel the ongoing action.

Updated documentation is here http://world.episerver.com/add-ons/episerver-forms/handling-events-for-episerver-forms/