From: es-discuss [mailto:[email protected]] On Behalf Of Tab
Atkins Jr.
> Cancellations should "chain"
This is the most important issue, in my mind. I often illustrate it with
```js
function fetchUser(id) {
return fetch(`/users/user/${id}`);
}
function fetchUserAsJSON(id) {
return fetchUser(id).then(JSON.parse);
}
```
If `fetchUser(1)` is cancellable but `fetchUserAsJSON(1)` is not, then I think
we've failed.
However, I think this still works with cancellation tokens:
```js
function fetchUser(id, canceller) {
return fetch(`/users/user/${id}`, { canceller });
}
function fetchUserAsJSON(id, canceller) {
return fetchUser(id, canceller).then(JSON.parse);
}
```
The API stays the same for both of them.
> Combinators should combine cancellations
Still works, I think, although again in a different form:
```js
function fetchUsers(ids, canceller) {
return Promise.all(ids.map(id => fetchUser(id, canceller)));
}
```
> You need to be able to "clean" a cancellable promise
Simple:
```js
function fetchUserUncancellable(id) {
return fetchUser(id); // no second argument
}
```
Overall I am more optimistic about cancellation tokens these days...
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
