React redux typings in typescript

redux-typing-example.ts

import { Dispatch } from 'redux';
import { ThunkAction } from 'redux-thunk';
import { getStore, IState } from './my_store';

let store = getStore();

// Create myThunkAction function with a type of ThunkAction<R, S, E>
let myThunkAction: ThunkAction<Promise<string>, IState, null> =
    (dispatch: Dispatch<IState>, getState: () => IState) => {
        return new Promise<string>((resolve, reject) => {

            // do async stuff with getState() and dispatch(), then...
            resolve('done!');

        });
    }

store.dispatch(myThunkAction)
.then(() => {
    // do stuff after the thunk has finished...
});

Basically the trick is to define your thunk function as a ThunkAction.

The ThunkAction<R, S, E> type is a generic type that takes 3 properties:

R - thunk function return type - it is a good idea to return a Promise from your thunk function so you can await the result if needed
S - State type - an interface that represents your redux store shape
E - extraArgument type - see https://twitter.com/dan_abramov/status/730053481919303685?lang=en

Taking notes from reduxjs/redux-thunk#103