update app code

docs/ytcg.js

@@ -1,13 +0,0 @@
-function getCover()
-{
-  var videoUrl = document.getElementById('videoUrl').value;
-  var videoCover = new Image();
-
-  videoCover.onload = function()
-  {
-    document.getElementById('ytImage').innerHTML =
-    '<a title="' + videoCover.width + 'x' + videoCover.height + '" href="' + videoCover.src + '" download="cover"><img src="'+ videoCover.src +'"></a>';
-  }
-
-  videoCover.src = 'https://img.youtube.com/vi/' + YouTubeGetID(videoUrl) + '/maxresdefault.jpg';
-}

src/ytcg.js

@@ -0,0 +1,21 @@
+function getCover()
+{
+  'use strict';
+
+  let videoUrl = document.getElementById('videoUrl').value;
+  let imageDiv = document.getElementById('ytImage');
+  imageDiv.innerHTML = '';
+
+  let videoCover = document.createElement('img');
+  let imageLink = document.createElement('a');
+
+  videoCover.src = 'https://img.youtube.com/vi/' + YouTubeGetID(videoUrl) + '/maxresdefault.jpg';
+  imageLink.href = videoCover.src;
+  imageLink.download = 'cover';
+  videoCover.onload = function() {
+    imageLink.title = videoCover.width + 'x' + videoCover.height;
+  }
+
+  imageLink.appendChild(videoCover);
+  imageDiv.appendChild(imageLink);
+}