Learning Redux

Thunk middleware

You may wonder what exactly the thunk middleware does. In fact, it is a very short function that checks whether an action is a function (that means whether we returned a function from an action creator). If that is the case, we call the function with dispatch and getState; otherwise, we simply call next:

const thunk = store => next => action =>  typeof action === 'function'    ? action(store.dispatch, store.getState)    : next(action)

It looks pretty simple, huh? Middleware is a simple, but powerful concept.