redux-actions-promise-wrapper/src/types.ts

Type safe wrapper for redux actions (compatible with redux-saga)

/**
 * Omit field of mapped type by value
 */
export type OmitByValue<O extends object, V> = Pick<
  O,
  ({ [P in keyof O]: O[P] extends V ? never : P })[keyof O]
>;

/**
 * Action with promise
 */
export type Action<
  T extends string = string,
  P = undefined,
  R = undefined
> = Readonly<{
  type: T;
  payload: P;
  promise: Promise<R>;
  resolve: (value: R) => void;
  reject: (reason?: any) => void;
}>;

/**
 * return type of generator function
 * @note
 * type Returnable<T> = { __returnedType?: T }; // * use this if dont need to check string and number literals
 */
export type GReturnable<T> = { __returnedType?: T } & T;

/**
 * Obtain return type of GeneratorFunction
 * @example
 * (...args: any[]) => IterableIterator<string | number | GReturnable<boolean>>
 * would have type boolean;
 */
export type GReturn<T> = T extends (...args: any) => IterableIterator<any>
  ? GeneratorReturnStrict<T>
  : undefined;
type GeneratorReturnStrict<
  T extends (...args: any) => IterableIterator<any>
> = ReturnType<T> extends IterableIterator<infer I>
  ? NonNullable<
      Extract<I, GReturnable<unknown>>['__returnedType']
    > extends never
    ? undefined
    : NonNullable<Extract<I, GReturnable<unknown>>['__returnedType']>
  : never;

/**
 * Obtain return type of IterableIterator (returned from Generator Function)
 * @example
 * IterableIterator<string | number | GReturnable<boolean>> -> boolean
 * IterableIterator<string | number> -> undefined
 */
export type IIReturn<T> = IterableIteratorReturn<T> extends never
  ? undefined
  : IterableIteratorReturn<T>;
type IterableIteratorReturn<T> = NonNullable<
  Extract<T, GReturnable<unknown>>['__returnedType']
>;

/**
 * Returned Promise Resolver
 * Get resolve type of Promise returned by a function
 */
export type rpResolve<T extends (...args: any[]) => any> = ReturnType<
  T
> extends Promise<infer U>
  ? U
  : T;