Redux reducer using object literal instead of a switch statement

reduxObjectLiteral.js

import {createStore} from 'redux';

const counter = (state = 0, action) => {
  const index = {
    'INCREMENT': () => {
        return state+1;
    },
    'DECREMENT': () => {
        return state-1;
    },
    'DEFAULT': () => {
        return state;
    }
  };
  return (index[action.type] || index['DEFAULT'])();
}

const store = createStore(counter);

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

store.dispatch({ type: 'INCREMENT' });
store.dispatch({ type: 'DECREMENT' });

Hi @sebjwallace

Quick question for you my friend :)

I am using the same technique, and I'm wondering if there is a good reason to make each property of index a function. Is this a way of obtaining immutability? I'm not sure why it is necessary, is the following identical? :

const counter = (state = 0, action) => ({
    'INCREMENT': state+1;
    'DECREMENT': state-1;
    'DEFAULT': state;
}[action.type] || 'DEFAULT']);

Did you try it? did it work?

That should work fine @SpaceCowboy20, but the syntax should be corrected:

const counter = (state = 0, action) => ({
    'INCREMENT': state+1,
    'DECREMENT': state-1,
    'DEFAULT': state
}[action.type || 'DEFAULT'])

The downside of this approach is that all three attributes are being computed, but only one will be used. Only a concern if performance is a concern.