Map RequestOptions in flow to RequestInit in TypeScript for fetch API

[Pike]

The optional second parameter in the fetch API has a mismatching type name in flow and ts, it'd be great if that could be translated.

https://github.com/facebook/flow/blob/a597d6df9bc221130f68437389a4d26d82e3726d/lib/bom.js#L1543

vs

https://github.com/microsoft/TypeScript/blob/ec77bff33226fb01f4e38b20e481f8c1fcd9e6c0/lib/lib.dom.d.ts#L18739

[Pike]

Maybe more importantly, also CredentialsType to RequestCredentials

[kevinbarabash]

Just to confirm:

RequestOptions -> RequestInit
CredentialsType -> RequestCredentials

I think I might add a way to provide these mappings via a config file as well that way people don't need to wait on changes to the tool itself.

[Pike]

Confirmed, and I like the idea of having a config file to map types, too.

Background, we're preparing mozilla/pontoon to be converted from flow to typescript, and run flow-to-ts in a github workflow, https://github.com/mozilla/pontoon/actions/workflows/frontend.yml?query=branch%3Amaster. The idea is that we'll be able to do the actual conversion with a minimal impact on the normal development. Having a config in-tree for type renames is going to be really helpful.

[kevinbarabash]

That's super cool! I hadn't thought about running it as a GitHub action. Thanks for sharing.