remove direct es6-promise dependency

[CharlesKuncheria]

Would you consider removing es6-promise dependency and let consumer provide es6-promise polyfill

[josh08h]

Bump.

[jonbern]

I agree that it would be great to be able to remove the es6-promise dependency.

Do you have any suggestions for an elegant way for the consumer to provide a promise polyfill?

As far as I can tell, it's currently only IE that lacks Promise functionality, which means it still needs to be provided for backwards functionality. At the same time, I feel that having to provide a Promise dependency in the constructor function is somewhat clunky.

Maybe it would be a better approach to try to find a more lightweight Promise polyfill? es6-promise is currently 315 kB, while promise-polyfill is 42.5 kB (https://www.npmjs.com/package/promise-polyfill).

[ptolemybarnes]

Hey @jonbern, what do you think about pushing the responsibility of polyfilling Promise on to the consumer? The way I see it fetch-retry is a small package for doing a very specific job and needn't be concerned with polyfilling the environment. https://github.com/matthew-andrews/isomorphic-fetch has the same policy (though perhaps bad example, looks unmaintained).

This would be a breaking change of course.

[jonbern]

I think that's a very valid point.

Given that all browsers except IE support promises, and also that IE is the only browser that doesn't support the Fetch API, I would think it should be safe to leave responsibility of adding the necessary polyfills to the user code.

https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

[ptolemybarnes]

I guess yet another option would be to offer 2 exports: one with the polyfill and one without (a bit like cross-fetch). That way you could avoid a breaking change. Still, for the reasons I already mentioned I would probably take the breaking change to remove the dependency altogether.

[jonbern]

I have created a new major version without the es6-promise dependency.

Thanks for bringing up the issue, and for providing valuable input and good suggestions.

https://github.com/jonbern/fetch-retry/releases/tag/4.0.0