hide_youtube_teaser_comment.js

// ==UserScript==
// @name         Hide YouTube teaser comment
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Hide YouTube teaser comment
// @author       calorie
// @match        https://www.youtube.com/*
// @grant        none
// ==/UserScript==

(function() {
  'use strict';

  async function getTeaserComment() {
    return new Promise((resolve) => {
      const interval = setInterval(() => {
        const comment = document.getElementById('comment-teaser');
        if (!comment) return;

        resolve(comment);
        clearInterval(interval);
      }, 100);
    });
  }

  async function init() {
    const comment = await getTeaserComment();
    comment.style.display = 'none';
  }

  init();
})();