applicationCache cheatsheet

if (window.applicationCache) {
  // "Naturally" reload when an update is available
  var cache = window.applicationCache
  var reload = false

  cache.addEventListener('updateready', () => {
    if (cache.status === cache.UPDATEREADY) {
      cache.swapCache()
      reload = true
    }
  }, false)

  setInterval(() => {
    try {
      // Nothing to update on first load; browsers error
      cache.update()
    } catch (e) { }
  }, 1000 * 60 * 60) // Every hour
}

window.applicationCache was removed from browsers; use Service Workers instead.

See: Service Worker API (developer.mozilla.org)