FormDataLike iterator type is incorrect

[Ethan-Arrowood]

The iterator type for FormDataLike is incorrect / too restrictive (

form-data-encoder/src/FormDataLike.ts

Line 43 in 8c8085d

[Symbol.iterator](): Generator<[string, FormDataEntryValue]>

). It uses Generator which makes methods throw and return required. But based on the spec, those two are optional for iterators (see here in MDN docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#throwexception) which are linked to in the source of FormDataLike itself.

I believe the types in undici are more accurate (https://github.com/nodejs/undici/blob/8050ec0224a51d44f776364820e6a16112fb4781/types/formdata.d.ts#L105 and https://github.com/nodejs/undici/blob/8050ec0224a51d44f776364820e6a16112fb4781/types/fetch.d.ts#L41-L47).

This is actually how I found this issue. I was trying to use the FormData object from Undici with the FormDataEncoder from this library.

[octet-stream]

Hi, thanks for your feedback. Yeah, this makes sense. TypeScript itself seem to use IterableIterator<T> for this method (see: https://github.com/microsoft/TypeScript/blob/d9d027d0c4f5044631a0c078166b8d01f41d28b5/src/lib/dom.iterable.generated.d.ts#L98). I was a little confused by the differences between Generator<T, TReturn, TNext>, Iterator<T> and IterableIterator<T> types. Though, I have no idea why undici needs their own typing for this.

[Ethan-Arrowood]

That's a good point. Not sure either. But I think switching to IterableIterator<T> will be good change nonetheless.

[octet-stream]

The fix is released with https://github.com/octet-stream/form-data-encoder/releases/tag/v3.0.1

[Ethan-Arrowood]

Incredible, thank you very much!