combineReducers(reducersMap)

• reducersMap: Object<string, ReducerFunction> – a map of keys to nested reducers, just like the combineReducers you would find in Redux itself.

Notes

Reducer composition is key to a clean Redux application. The built-in Redux combineReducers won't work for nested reducers that use loop, so we included one that is aware that some reducers might have side effects. The combineReducers in redux-loop knows how to compose cmd objects as well as state objects from nested reducers so that your effects-tree is always separate from your state-tree. Redux-loop's combineReducers function is completely compatible with the one from Redux, so there should be no issues switching to this implementation (if, for example, something out of your control is using Redux's combineReducers method and does not generate cmd objects).

Examples

Standard example

import { combineReducers } from 'redux-loop';
import reducerWithSideEffects from './reducer-with-side-effects';
import plainReducer from './plain-reducer';

export default combineReducers({
  withEffects: reducerWithSideEffects,
  plain: plainReducer
});

Passing extra params

If you pass extra parameters to the reducer returned by combineReducers, they will be passed through to each nested reducer.

function reducer1(state = {}, action, arg){
  console.log(arg);
  return state;
}

function reducer2(state = {}, action, arg){
  console.log(arg); 
  return state;
}

const reducer = combineReducers({reducer1, reducer2});
reducer(undefined, {type: 'foo'}, 'abc');
//abc will be logged twice (once for reducer1 and once for reducer2)

Using Immutable.js

If you're using immutable.js with your reducer, you'll want to use the ImmutableJS version of combineReducers from the redux-loop-immutable package. It has the same API as the non-immutable version except that the state it returns is an Immutable Map instead of an Object.

import { combineReducers } from 'redux-loop-immutable';
import reducerWithSideEffects from './reducer-with-side-effects';
import plainReducer from './plain-reducer';

export default combineReducers({
  withEffects: reducerWithSideEffects,
  plain: plainReducer
});