Redux-toolkit: `extraReducers` type problem

[yhnavein]

Hi,

I wanted to check out the new createAsyncThunk and I stumbled with the following issue raised by TypeScript:

I can write [loadDates.fulfilled as any] to get rid of this error, but this feel very off.
Am I doing something wrong?

I am using "typescript": "3.8.3"

[phryneas]

https://redux-toolkit.js.org/usage/usage-with-typescript/#type-safety-with-extrareducers

@markerikson This seems to confuse people all the time - what are your thoughts on making the builder notation the default in the documentation?

[rrebase]

You could also use the type explicitly e.g [loadDates.fulfilled.type]

[phryneas]

He could, but then he wouldn't have inferred action types. Using the map object notation with TypeScript is pretty much useless.

[markerikson]

I don't think we need to make it the _default_ in the docs, but I do think we should update both the createReducer and createSlice#extraReducers sections in the API reference with examples of both syntaxes, and emphasize there that the builder notation is preferred for TS usage.

[markerikson]

Covered by #460 .