Get all event listeners from chrome.

evts.js

// This is to list all events on the page:
[].slice.call(document.querySelectorAll('*'))
  .map(el => ({ el, listeners: Object.entries(getEventListeners(el)) }))
  .filter(el => el.listeners.length)

// Use with a mutationobserver to confirm that events are detaching:
const _getEventListeners = getEventListeners
const getAll = () => [].slice.call(document.querySelectorAll('*'))
  .map(el => ({ el, listeners: Object.entries(_getEventListeners(el)) }))
  .filter(el => el.listeners.length)

let tick
new MutationObserver(muts => {
  const valid = muts.filter(({ type }) => type === 'childList')

  if (valid.length && !tick) {
    window.requestAnimationFrame(() => {
      const list = getAll()
      console.log('There are %d listeners', list.length, list)
      window.requestAnimationFrame(() => (tick = false))
    })

    tick = true
  }
}).observe(document.documentElement, { childList: true, subtree: true })