Update assets/js/watched_widget.js with suggestion of AHOHNMYC

Co-authored-by: AHOHNMYC <24810600+AHOHNMYC@users.noreply.github.com>

assets/js/watched_widget.js

@@ -39,11 +39,9 @@ function get_all_video_times() {
     return helpers.storage.get(save_player_pos_key) || {};
 }
 
-var watchedIndicators = document.getElementsByClassName('watched-indicator');
-for (var i = 0; i < watchedIndicators.length; i++) {
-    var indicator = watchedIndicators[i];
-    var watched_part = get_all_video_times()[indicator.getAttribute('data-id')];
-    var total = parseInt(indicator.getAttribute('data-length'), 10);
+document.querySelectorAll('.watched-indicator').forEach(function (indicator) {
+    var watched_part = get_all_video_times()[indicator.dataset.id];
+    var total = parseInt(indicator.dataset.length, 10);
     if (watched_part === undefined) {
         watched_part = total;
     }
@@ -57,4 +55,4 @@ for (var i = 0; i < watchedIndicators.length; i++) {
     }
 
     indicator.style.width = percentage + '%';
-}
+});