feat: support old YouTube layout

src/content-script.js

@@ -1,15 +1,35 @@
+/**
+ * List of selectors to retrieve the channel homepage address from the DOM.
+ * Supports both new and old YouTube layouts.
+ * @type {Array}
+ */
+const CHANNEL_URL_SELECTORS = [
+    'yt-formatted-string#owner-name :first-child',
+    '.yt-user-info :first-child',
+];
+
+/**
+ * Check if the provided input is nil (`null` or `undefined`)
+ * @param {*} input The input to test
+ * @returns {boolean} `true` if the input is nil, `false` otherwise
+ */
+function isNil(input) {
+    return input === null || input === undefined;
+}
+
 /**
  * Retrieve the YouTube channel URL from the DOM.
  * @returns {(string|null)} The URL of the channel or `null` if not found
  */
 function findChannelAddress() {
-    const ELEMENT = 'yt-formatted-string';
-    const ID = 'owner-name';
-    const container = window.document.querySelector(`${ELEMENT}#${ID}`);
-    if (container !== undefined && container.firstChild.href !== undefined) {
-        return container.firstChild.href;
+    let channelAddress = null;
+    // eslint-disable-next-line
+    for (let urlSelector of CHANNEL_URL_SELECTORS) {
+        if (!isNil(channelAddress)) break;
+        const container = window.document.querySelector(urlSelector);
+        if (!isNil(container)) channelAddress = container.href;
     }
-    return null;
+    return channelAddress;
 }
 
 // Notify the extension by returning the found URL