trigger userContent change without killing ie8

Change-Id: I876006c0cabdb45ac2695b0061913f4f38d5a5a9
Reviewed-on: https://gerrit.instructure.com/9699
Reviewed-by: Zach Wily <zach@instructure.com>
Tested-by: Hudson <hudson@instructure.com>

app/coffeescripts/discussions/EntryView.coffee

@@ -10,12 +10,13 @@ define [
   'compiled/discussions/EntryEditor'
   'compiled/discussions/MarkAsReadWatcher'
   'str/htmlEscape'
+  'vendor/jquery.ba-tinypubsub'
   'compiled/jquery.kylemenu'
 
   # entry_with_replies partials
   'jst/_avatar'
   'jst/discussions/_reply_form'
-], (require, I18n, Backbone, EntryCollection, entryContentPartial, deletedEntriesTemplate, entryWithRepliesTemplate, Reply, EntryEditor, MarkAsReadWatcher, htmlEscape) ->
+], (require, I18n, Backbone, EntryCollection, entryContentPartial, deletedEntriesTemplate, entryWithRepliesTemplate, Reply, EntryEditor, MarkAsReadWatcher, htmlEscape, {publish}) ->
 
   # save memory
   noop = ->
@@ -84,11 +85,11 @@ define [
       @$el.html entryWithRepliesTemplate @model.toJSON()
       @$el.attr 'data-id', @model.get 'id'
       @$el.attr 'id', @model.cid
-      super
 
       # enhance the media_comments in the message
-      $(document).trigger('user_content_change')
+      publish('userContent/change')
 
+      super
 
     openMenu: (event, $el) ->
       @createMenu($el) unless @$menu

public/javascripts/instructure.js

@@ -486,7 +486,16 @@ define([
         alert(I18n.t('alerts.file_previews_disabled', 'File previews have been disabled for this Canvas site'));
       });
     }
-    $(document).bind('user_content_change', $.throttle(50, enhanceUserContent));
+
+    // publishing the 'userContent/change' will run enhanceUserContent at most once every 50ms
+    var enhanceUserContentTimeout;
+    $.subscribe('userContent/change', function(){
+      clearTimeout(enhanceUserContentTimeout);
+      enhanceUserContentTimeout = setTimeout(enhanceUserContent, 50);
+    });
+
+
+    $(document).bind('user_content_change', enhanceUserContent);
     setInterval(enhanceUserContent, 15000);
     setTimeout(enhanceUserContent, 1000);
 

public/javascripts/vendor/jquery.ba-tinypubsub.js

@@ -11,17 +11,17 @@ define(['jquery'], function($){
 
   // Create a "dummy" jQuery object on which to bind, unbind and trigger event
   // handlers. Note that $({}) works in jQuery 1.4.3+.
-  var o = $({});
+  var o = $({}), subscribe, unsubscribe, publish;
 
   // Subscribe to a topic. Works just like bind, except the passed handler
   // is wrapped in a function so that the event object can be stripped out.
   // Even though the event object might be useful, it is unnecessary and
   // will only complicate things in the future should the user decide to move
   // to a non-$.event-based pub/sub implementation.
-  $.subscribe = function( topic, fn ) {
+  $.subscribe = subscribe = function( topic, fn ) {
     if ($.isPlainObject(topic)) {
       return $.each(topic, function(topic, fn) {
-        $.subscribe(topic, fn);
+        subscribe(topic, fn);
       });
     }
     // Call fn, stripping out the 1st argument (the event object).
@@ -38,13 +38,19 @@ define(['jquery'], function($){
   };
 
   // Unsubscribe from a topic. Works exactly like unbind.
-  $.unsubscribe = function() {
+  $.unsubscribe = unsubscribe = function() {
     o.unbind.apply( o, arguments );
   };
 
   // Publish a topic. Works exactly like trigger.
-  $.publish = function() {
+  $.publish = publish = function() {
     o.trigger.apply( o, arguments );
   };
 
+  return {
+    subscribe: subscribe,
+    unsubscribe: unsubscribe,
+    publish: publish
+  };
+
 });