Return Type of a `Yield Call`
I've Noticed That the Result of a Yield Call Effect Is Typed as Any When Used as Const Data = Yield Call(F); While F Is a () => Promise Function. Am I Missing...
I've noticed that the result of a yield call effect is typed as any when used as
const data = yield call(f);
while f is a () => Promise<number> function.
Am I missing something or is it a redux-saga typings limitation?
4 Answers
Check this ongoing thread, tldr; it's a typescript limitation
In the meantime, you can use this package instead: typed-redux-saga
Before
import { call, all } from "redux-saga/effects";
...
// Api.fetchUser return User
// but user has type any
const user = yield call(Api.fetchUser, action.payload.userId);
After
import { call, all } from "typed-redux-saga";
...
// user now has the correct type User
// NOTE: it's yield*, not yield
const user = yield* call(Api.fetchUser, action.payload.userId);
define this types
export type PromiseFn = (...args: any) => Promise<any>;
export type GetT<T> = T extends Promise<infer N> ? N : any;
export type GetFnResult<T extends PromiseFn> = GetT<ReturnType<T>>;
then
const data: GetFnResult<typeof f> = yield call(f);
You can use
const data = (yield call(f)) as number
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
