Subscribe to url change

onLocationChange.js

const onLocationChange = (() => {
  const subscribers = []
  const fireEvent = () => subscribers.forEach(sub => sub())

  const { pushState, replaceState } = window.history

  window.history.pushState = function(...args) {
    pushState.apply(window.history, args)
    fireEvent()
  }

  window.history.replaceState = function(...args) {
    replaceState.apply(window.history, args)
    fireEvent()
  }

  window.addEventListener('popstate', fireEvent)

  return subscriber => subscribers.push(subscriber)
})()