different dom ready implementations in vanilla javascript

dom-content-loaded.js

function ready (fn) {
  if (typeof fn !== 'function') return
  if (document.readyState === 'complete') return fn()
  document.addEventListener('DOMContentLoaded', fn, false)
}

example.js

ready(function domIsReady() {
  console.info('dom is ready now')
})

request-animation-frame.js

function ready (fn, {requestAnimationFrame} = window) {
  if (document.body) return fn()
  requestAnimationFrame(ready.bind(null, fn, {requestAnimationFrame}))
}