a js script to embed youtube videos when a youtube url is present

youtube-embedder.user.js

// ==UserScript==
// @name         youtube embedder
// @version      2.0.3
// @namespace    https://gist.github.com/chadlavi/27c08ea6648d375c3f5de3ec7f43a015
// @downloadURL  https://gist.github.com/chadlavi/27c08ea6648d375c3f5de3ec7f43a015/raw/youtube-embedder.user.js
// @updateURL  https://gist.github.com/chadlavi/27c08ea6648d375c3f5de3ec7f43a015/raw/youtube-embedder.user.js
// @description  embed youtube videos when a url is present
// @author       Chad Lavimoniere
// @exclude      http*://*youtube.com*
// @exclude      http*://*facebook.com*
// @exclude      http*://*twitter.com*
// @exclude      http*://mltshp.com*
// @exclude      http*://news.ycombinator.com/*
// @exclude      http*://*.duckduckgo.com/*
// @exclude      http*://6.*.org/*
// @include      http*://*.*
// @grant        none
// ==/UserScript==

(() => {
  'use strict'

  function $e(t='div',p={},c=[]){
    let el=document.createElement(t)
    Object.assign(el,p)
    el.append(...c)
    return el
  }

  const youtubeEmbed = (link) => {
    const url = link.href.replace(/m\.youtube/, 'youtube')
      .replace(/watch\?[^v]*v=/, 'embed/')
      .replace(/\&.*$/, '')
      .replace(/youtu\.be/, 'youtube.com/embed/')
    const embed = $e(
      'div',
      {
        className: 'greasemonkey-youtube-embed'
      }, 
      [
        $e('br'),
        $e(
          'div',
          {
            style: 'float: none; clear: both; width: 100%; position: relative; padding-bottom: 56.25%; padding-top: 25px; height: 0;',
          },
          [
            $e(
              'object',
              {
                style: 'position: absolute; top: 0; left: 0; width: 100%; height: 100%;',
                data: url,
              }
            )
          ]
        ),
        $e('br')
      ]
    )
    link.parentNode.insertBefore(embed, link)
  }

  const links = document.links
  for (let i=0; i<links.length; i++){
    const link = links[i]
    const {href, innerHTML, className} = link
    if ((
      href.match(/youtube.com\/watch/g)
      || href.match(/^youtu\.be\/.*/)
      || href.match(/^http.?:\/\/youtu\.be\/.*/)
    ) && !innerHTML.match(/</)) {
      if (window.location.host.match(/reddit.com/)) {
        if (!(className.match(/title/i) || className.match(/thumb/))) {
          youtubeEmbed(link)
          console.log(i+', '+link)
        }
      } else {
        youtubeEmbed(link)
        console.log(i+', '+link)
      }
    }
  }
})()