Re: [fetch] Aborting a fetch (#27)

FYI I've updated the code so that you can provide a value when canceled.

```js
// will be resolved
new Promise(function ($res, $rej, ifCanceled) {
  var internal = setTimeout($rej, 1000);
  ifCanceled(function () {
    clearTimeout(internal);
  });
})
// will be resolved without executing
.then(
  function () {
    console.log('on time');
  },
  function () {
    console.log('error');
  }
)
.cancel({beacuse:'reason'})
// will simply execute and resolve
.then(function (value) {
  console.log(value);
});
```

Invoking cancel again can be done internally (`ifCanceled` returns such method) or externally so the first in charge of canceling will be also eventually in charge of passing an arbitrary resolution for such cancellation.

@getify I'm using timers and events to test this stuff, I don't even care much about fetch itself in terms of solution. fetch is just Yet Another Case when you want to cancel something at any time.

---
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/27#issuecomment-87695054