Unfortunately Promises need to be fixed before fetch will be sane and here's how the promises spec currently looks:

- unhandled errors silently swallowed [1] (this is the case for the most popular polyfill [1] too - the one recommended by fetch polyfills, BEWARE [3])

- no 'finally' method, despite pretty much everything in a UI needing some common 'cleanup' after e.g. a fetch()

- not cancellable

Right now you're better off with `$.ajax` (maybe make a custom build of jQuery) or a promise-like library like reqwest [2], rather than fighting with fetch.

[1] https://github.com/stefanpenner/es6-promise/issues/70#issuec...

[2] https://github.com/ded/reqwest

[3] http://requirebin.com/?gist=8f13d5147c1c252ab1691115bfa8b7c5

I don't know why they pushing Observables AND Promises in ECMAScript. Observables a much more flexible and don't have these problems :/

That depends on whether the Promise specification gets cancellations. I like fetch's clean API, but being able to cancel my ajax requests is essential.

Cancel the requests, or cancel the callback chain that's set up to fire when they complete?

Essential? Why?

The big use-case I can think of is file uploads. If someone is uploading a large file, you wanna be able to cancel it.