Re: [heycam/webidl] add a type to represent the undefined value (#60)

In our case it was a promise that resolves with `Response` or undefined.

```js
caches.match(url).then(response => …);
```

If no match is found, it resolves undefined. We've had to go with "any" to work around it, which isn't very readable.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/heycam/webidl/issues/60#issuecomment-258839676