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WaitForKeyElement

Waits for an element using the MutationObserver API

此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.cn-greasyfork.org/scripts/523012/1519437/WaitForKeyElement.js 

  1. // ==UserScript==
  2. // @name         WaitForKeyElement
  3. // @namespace    Violentmonkey Scripts
  4. // @version      1.1
  5. // @description  Waits for an element using the MutationObserver API
  6. // @author       PaywallDespiser
  7. // @grant        none
  8. // ==/UserScript==
  9.  
  10. /**
  11.  * Waits for a element of a given selector.
  12.  *
  13.  * @param {string} selector
  14.  * @param {Element} [target=document.body]
  15.  * @returns {Promise<Element>}
  16.  */
  17. function waitForKeyElement(selector, target = document.body) {
  18.     return new Promise((resolve) => {
  19.         {
  20.             const element = target.querySelector(selector);
  21.             if (element) {
  22.                 return resolve(element);
  23.             }
  24.         }
  25.  
  26.         const observer = new MutationObserver((mutations) => {
  27.             for (const mutation of mutations) {
  28.                 for (const node of mutation.addedNodes) {
  29.                     if (!(node instanceof HTMLElement)) continue;
  30.  
  31.                     if (node.matches(selector)) {
  32.                         observer.disconnect();
  33.                         resolve(node);
  34.                         return;
  35.                     }
  36.                     const childElement = node.querySelector(selector);
  37.                     if (childElement) {
  38.                         observer.disconnect();
  39.                         resolve(childElement);
  40.                         return;
  41.                     }
  42.                 }
  43.             }
  44.         });
  45.  
  46.         observer.observe(target, {
  47.             childList: true,
  48.             subtree: true,
  49.             attributes: false,
  50.             characterData: false,
  51.         });
  52.     });
  53. }