Update player.js

recommitted code-charity#1813 (with some minor changes)

js&css/web-accessible/www.youtube.com/player.js

@@ -725,15 +725,26 @@ ImprovedTube.playerPopupButton = function () {
 			child: svg,
 			opacity: 0.8,
 			onclick: function () {
-				var player = ImprovedTube.elements.player;
-
-				player.pauseVideo();
-
-				let urlPopup = `${location.protocol}//www.youtube.com/embed/${location.search.match(ImprovedTube.regex.video_id)[1]}?start=${parseInt(player.getCurrentTime())}&autoplay=${(ImprovedTube.storage.player_autoplay ?? true) ? '1' : '0'}`;
-				const listMatch = location.search.match(ImprovedTube.regex.playlist_id);
-				if (listMatch) urlPopup += `&list=${listMatch[1]}`;
-
-				window.open(urlPopup, '_blank', `directories=no,toolbar=no,location=no,menubar=no,status=no,titlebar=no,scrollbars=no,resizable=no,width=${player.offsetWidth},height=${player.offsetHeight}`);
+				const ytPlayer = ImprovedTube.elements.player;
+
+				ytPlayer.pauseVideo();
+
+				const videoID = location.search.match(ImprovedTube.regex.video_id)[1],
+					listMatch = location.search.match(ImprovedTube.regex.playlist_id),
+					popup = window.open(
+						`${location.protocol}//www.youtube.com/embed/${videoID}?start=${parseInt(ytPlayer.getCurrentTime())}&autoplay=${(ImprovedTube.storage.player_autoplay ?? true) ? '1' : '0'}${listMatch?`&list=${listMatch[1]}`:''}`,
+						'_blank',
+						`directories=no,toolbar=no,location=no,menubar=no,status=no,titlebar=no,scrollbars=no,resizable=no,width=${ytPlayer.offsetWidth},height=${ytPlayer.offsetHeight}`
+					);
+
+				if(popup && listMatch){
+					//! If the video is not in the playlist or not within the first 200 entries, then it automatically selects the first video in the list.
+					popup.addEventListener('load', function () {
+						//~ check if the video ID in the title link matches the original video ID in the URL and if not remove the playlist from the URL (reloads the page).
+						const videoLink = popup.document.querySelector('div#player div.ytp-title-text>a[href]');
+						if (videoLink && videoLink.href.match(ImprovedTube.regex.video_id)[1] !== videoID) popup.location.search = popup.location.search.replace(/(\?)list=[^&]+&|&list=[^&]+/, '$1');
+					}, {passive: true, once: true});
+				}
 			},
 			title: 'Popup'
 		});