Add comment to explain null value in AudioPlayerService. (oppia#4735)

nithusha21 · Feb 24, 2018 · c3e9a24 · c3e9a24
1 parent e7bdfce
commit c3e9a24
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/core/templates/dev/head/services/AudioPlayerService.js b/core/templates/dev/head/services/AudioPlayerService.js
@@ -42,6 +42,10 @@ oppia.factory('AudioPlayerService', [
             // to grab native audio.
             // TODO(tjiang11): Look for a better way to handle this.
             $timeout(function() {
+              // _currentTrack could be null if the learner stops audio
+              // shortly after loading a new card or language. In such
+              // cases, we do not want to attempt setting the 'onended'
+              // property of the audio.
               if (_currentTrack !== null) {
                 _currentTrack.audio.onended = function() {
                   _currentTrack = null;