Redux thunk, where does dispatch come from in an action?

Question

React

where can we use dispatch? this is a method of the store, why then we call not in its context? in the dispatch component comes through the context, and where it comes from in the action from the example below which is from the redux-thunk docks, for me it looks like it comes from window.

const INCREMENT_COUNTER = 'INCREMENT_COUNTER';

function increment() {
  return {
    type: INCREMENT_COUNTER
  };
}

function incrementAsync() {
  return dispatch => {
    setTimeout(() => {
      // Yay! Can invoke sync or async actions with `dispatch`
      dispatch(increment());
    }, 1000);
  };
}

Answer 1

It comes from the redux-thunk
middleware Let's look at the source code:

function createThunkMiddleware(extraArgument) {
  return ({ dispatch, getState }) => next => action => {
    if (typeof action === 'function') {
      return action(dispatch, getState, extraArgument);
    }

    return next(action);
  };
}

In which it is clear that if the returned action type is a function, then call everything the same, but with arguments (dispatch, getState and extraArgument) - which are available through the scope and are what you need.