Hacky way to auto advance Udacity's classroom lecture videos

udacity-auto-advance.user.js

// ==UserScript==
// @name Udacity Auto Advance
// @namespace https://omscs.gatech.edu/
// @description Auto advance Udacity's classroom lecture videos
// @date 2017.01.25
// @version 1.0.1
// @match https://classroom.udacity.com/*
// @run-at document-end
// @run_at document_end
// @grant none
// ==/UserScript==

const checkMe = link => {
  if (link.innerText.trim().toLowerCase() === 'play next' &&
    link.className.trim().toLowerCase().startsWith('_auto-advance-overlay--button--')) {
    link.click()
  }
}

const checkInsideMe = parent => {
  const links = parent.getElementsByTagName('a')
  for (let i = 0, length = links.length; i < length; i++) {
    checkMe(links[i])
  }
}

const observer = new MutationObserver(mutations => {
  for (let i = 0, length = mutations.length; i < length; i++) {
    if (mutations[i].target.nodeName === 'A') {
      checkMe(mutations[i].target)
    }
    for (let j = 0, len = mutations[i].addedNodes.length; j < len; j++) {
      switch (mutations[i].addedNodes[j].nodeName) {
        case 'A':
          checkMe(mutations[i].addedNodes[j])
          break
        case 'DIV':
          checkInsideMe(mutations[i].addedNodes[j])
          break
      }
    }
  }
})

observer.observe(document, { childList: true, subtree: true })