Use Eventbrite widget container (#850)

* Use Eventbrite widget container

* remove JS to detect missing eventbrite iframe

_includes/javascript.html

@@ -37,13 +37,6 @@
     show_instructions();
 });
 
-  // detect misssing iframe for Eventbrite
-  $(document).ready(function(){
-      if ($('iframe').height() == 0) {
-          $('iframe').before('<p>Looks like your adblocker blocked the registration window. Please navigate to <a href="https://www.eventbrite.com/tickets-external?eid={{page.eventbrite}}&ref=etckt">https://www.eventbrite.com/tickets-external?eid={{page.eventbrite}}&ref=etckt</a> to register.</p>');
-      }
-  });
-
   // hide alerts when site is rendered on carpentries.github.io
   $(document).ready(function() {
       if (location.href.startsWith("https://carpentries.github.io/workshop-template/")) {

index.md

@@ -94,13 +94,16 @@ displayed if the 'eventbrite' field in the header is not set.
 {% if page.eventbrite %}
 <strong>Some adblockers block the registration window. If you do not see the
   registration box below, please check your adblocker settings.</strong>
-<iframe
-  src="https://www.eventbrite.com/tickets-external?eid={{page.eventbrite}}&ref=etckt"
-  frameborder="0"
-  width="100%"
-  height="280px"
-  scrolling="auto">
-</iframe>
+<div id="eventbrite-widget-container"></div>
+<script src="https://www.eventbrite.com/static/widgets/eb_widgets.js"></script>
+<script type="text/javascript">
+    window.EBWidgets.createWidget({
+        // Required
+        widgetType: 'checkout',
+        eventId: {{eventbrite}},
+        iframeContainerId: 'eventbrite-widget-container',
+    });
+</script>
 {% endif %}