Kill requests for loading responses when selecting another thread. This ensures…

Kill requests for loading responses when selecting another thread. This ensures that the thread you're viewing has the right responses loaded.

lms/static/coffee/src/discussion/discussion_router.coffee

@@ -26,6 +26,7 @@ if Backbone?
       @thread = @discussion.get(thread_id)
       @setActiveThread()
       if(@main)
+        @main.cleanup()
         @main.undelegateEvents()
 
       @main = new DiscussionThreadView(el: $(".discussion-column"), model: @thread)

lms/static/coffee/src/discussion/utils.coffee

@@ -71,7 +71,7 @@ class @DiscussionUtil
           params["loadingCallback"].apply(params["$loading"])
         else
           params["$loading"].loading()
-    $.ajax(params).always ->
+    request = $.ajax(params).always ->
       if $elem
         $elem.removeAttr("disabled")
       if params["$loading"]
@@ -79,6 +79,7 @@ class @DiscussionUtil
           params["loadedCallback"].apply(params["$loading"])
         else
           params["$loading"].loaded()
+    return request
 
   @get: ($elem, url, data, success) ->
     @safeAjax

lms/static/coffee/src/discussion/views/discussion_thread_view.coffee

@@ -23,10 +23,15 @@ if Backbone?
       @renderResponses()
       @
 
+    cleanup: ->
+      if @responsesRequest?
+        @responsesRequest.abort()
+
     renderResponses: ->
-      DiscussionUtil.safeAjax
+      @responsesRequest = DiscussionUtil.safeAjax
         url: "/courses/#{$$course_id}/discussion/forum/#{@model.get('commentable_id')}/threads/#{@model.id}"
         success: (data, textStatus, xhr) =>
+          @responsesRequest = null
           @$el.find(".loading").remove()
           Content.loadContentInfos(data['annotated_content_info'])
           comments = new Comments(data['content']['children'])