Re: [ServiceWorker] Returning a FetchPromise from fetch() (#625)

I have a question: 

```js
var p = waitForUserConfirm('press OK to continue').then(() => fetch(url));
```

Since a generic `Promise#then` would "cast" a `FetchPromise` to a generic `Promise`,  `p` will not have the `abort` method, in this case how can I abort the fetch?

For this, I like the `CancellationToken` approach more since it gives control wherever a `fetch` sits in an async operation chain

```js
var token = new CancellationToken();
var p = waitForUserConfirm('press OK to continue').then(() => fetch(url, token));
app.on('navigate', token.requestCancel); // possible to cancel fetch when navigate to another page
```

---
Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/625#issuecomment-76350167