redux_async.js

class App extends React.Component {
  render() {
    return (
      <div>
        <button onClick={this.props.async_update}>Click To Update State After Five Seconds</button>
      </div>
    );
  }
}

const ConnectedApp = connect(
  (state) => {
    return { ...state };
  },
  (dispatch) => {
    return {
      async_update: () => {
        setTimeout(() => {
          dispatch({type: UPDATE}, payload: "new_value" ), 5000
        };
    }
})(App);
        
const reducer = (state = { current_state: "Old State"}, action) => {
  switch (action.type) {
    case UPDATE:
      return { ...state, current_state: action.payload };
    default:
      return state;
    }
};