+var possibly_play_sound = function(old_data, new_data) {
+ if (!enable_sound) {
+ return;
+ }
+ if (old_data === null) {
+ return;
+ }
+ var ding = document.getElementById('ding');
+ if (ding && ding.play !== undefined) {
+ if (old_data['position'] && old_data['position']['fen'] &&
+ new_data['position'] && new_data['position']['fen'] &&
+ (old_data['position']['fen'] !== new_data['position']['fen'] ||
+ old_data['position']['move_num'] !== new_data['position']['move_num'])) {
+ ding.play();
+ }
+ }
+}
+