Re: [w3c/ServiceWorker] Provide a one-line way to listen for a waiting Service Worker (#1222)

I suggest this "prolyfill" (a forward-looking polyfill for behavior to be eventually standardized)

```js
if (!('waiting' in navigator.serviceWorker)) {
  navigator.serviceWorker.waiting = new Promise(function(resolve) {
    navigator.serviceWorker.ready.then(function(reg) {
      function awaitStateChange() {
        reg.installing.addEventListener('statechange', function() {
          if (this.state === 'installed') resolve(reg);
        });
      }
      if (reg.waiting) resolve(reg);
      if (reg.installing) awaitStateChange();
      reg.addEventListener('updatefound', awaitStateChange);
    })
  });
}
```

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/ServiceWorker/issues/1222#issuecomment-351566460