From 6e284ce2590bc625ab504808e96f8c951181bed5 Mon Sep 17 00:00:00 2001
From: sup39 <dev@sup39.dev>
Date: Tue, 30 Jan 2024 08:38:54 +0900
Subject: [PATCH] fix: `untilElementLoaded()` when element already exists

---
 index.js | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/index.js b/index.js
index 3565d9c..72644fd 100644
--- a/index.js
+++ b/index.js
@@ -1,11 +1,10 @@
 // ==UserScript==
 // @name         sup-ytsync
-// @namespace    http://tampermonkey.net/
-// @version      0.1.0
-// @description  sup39
+// @namespace    https://forgejo.sup39.dev/sup39/sup-ytsync/
+// @version      2024-01-30
+// @description  A script to sync Youtube video progress with others via MQTT
 // @author       sup39
 // @match        https://www.youtube.com/watch*
-// @icon         https://www.google.com/s2/favicons?sz=64&domain=youtube.com
 // @grant        none
 // ==/UserScript==
 
@@ -162,24 +161,25 @@
     });
   });
 
-  // Based on https://stackoverflow.com/a/61511955 by Yong Wang (2020)
   /**
    * @param {string} selector
+   * @param {Element} root
    * @returns {Promise<Element>}
    */
-  const untilElementLoaded = selector => new Promise(resolve => {
-    const elm = document.querySelector(selector);
-    if (elm != null) return elm;
-
+  // https://stackoverflow.com/a/61511955
+  const untilElementLoaded = (selector, root=document.body) => new Promise(resolve => {
+    // resolve immediately if element already exists
+    const elm = root.querySelector(selector);
+    if (elm != null) return resolve(elm);
+    // observe root until element presents
     const observer = new MutationObserver(() => {
-      const elm = document.querySelector(selector);
+      const elm = root.querySelector(selector);
       if (elm != null) {
         observer.disconnect();
         resolve(elm);
       }
     });
-
-    observer.observe(document.body, {
+    observer.observe(root, {
       childList: true,
       subtree: true
     });