Why does it says that 'next' is not defined in redux middleware code. Is next method of middleware deprecated?

Question

I am getting this error:

index.js?dadc:6Uncaught TypeError: next is not a function

Is the next method used by middleware in ReactJS deprecated or have I used it incorrectly?

import { applyMiddleware, combineReducers , createStore } from 'redux';

const logger =(store) => (next) => (action) => {

    console.log('middle-ware called');
    next(action);

}

const reducer=(state ,action)=>{
    if(action.type=='INC'){
        console.log('a-----------------',action);
        return state+action.payload;
    }
    else
        return state; };

const store=createStore(reducer ,1 ,applyMiddleware(logger()));



store.subscribe(()=>{
    console.log('store changed',store.getState()) });

store.dispatch({type :'INC' ,payload : 10}); store.dispatch({type :'INC' ,payload : 10});

what happen if you `console.log` the value of `next` in `logger`? — martriay, Sep 04 '16 at 07:04

score 5 · Accepted Answer · answered Sep 04 '16 at 07:42

5

That's not working because you are passing to applyMiddleware the returned value of logger() with no arguments.

To fix it, you have to pass logger instead of logger() to applyMiddleware().

You can read more about custom middlewares here

answered Sep 04 '16 at 07:42

QoP

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I solved my post https://stackoverflow.com/questions/72978999/redux-middleware-with-configurestore-next-is-not-a-function with your soution. Thank you – sineverba Jul 18 '22 at 07:46

score 0 · Answer 2 · answered Mar 10 '23 at 17:04

0

In my case, I was trying to pass an enhancer as middleware. Moving the enhancer from middleware to enhancers fixed the problem.https://redux-toolkit.js.org/api/configureStore#enhancers

answered Mar 10 '23 at 17:04

ItsGeorge

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Why does it says that 'next' is not defined in redux middleware code. Is next method of middleware deprecated?

2 Answers2

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