MENU


applyMiddleware()

The middleware signature is ({ getState, dispatch }) => next => action

next(action), when invoking the reducer at the last stage of the pipeline, returns the action itself, and not the updated state. The call is synchronous.
RESETRUNFULL
<!DOCTYPE html>
<html>
   <head>
      <script src="https://unpkg.com/redux@latest/dist/redux.min.js"></script>
   </head>
   <body>
      <button onclick="store.dispatch({type: 'multiply', factor: 10})">Dispatch</button>
      <script>
         const reducer = (state, action) => {
            alert(state);
            return (action.type=="multiply") ? state * action.factor : state;
         };
         const alerter = ({ getState }) => next => action => {
            alert(getState()+" ...before");
            const v = getState() * next(action).factor;
            alert(v+" ...after");
            return action;
         };
         const store = Redux.createStore(reducer, 1, Redux.applyMiddleware(alerter, alerter));         
      </script>
   </body>
</html>