Redux Reducer Handlers

A library for converting Reducer switch statements to a dictionary map of handlers, which are simply callbacks that can directly modify the passed in state.

Instead of defining a Reducer like this:

const SET_FAVORITE_CHIPS = 'chips/SET_FAVORITE_CHIPS';
const SET_CHIPS_FOR_SALE = 'chips/SET_CHIPS_FOR_SALE';

const initialState = {
  favorite: '',
  forSale: ['BBQ', 'Sea Salt', 'Plain', 'Jalepeno']
};

function reducer(state = initialState, action) {
  switch (action.type) {
    case SET_FAVORITE_CHIPS:
      return { ...state, favorite: action.payload };
    case SET_CHIPS_FOR_SALE:
      return { ...state, forSale: action.payload };
    default:
      return state;
  }
}

You define them as Handler functions. Handler functions are passed a mutable, draft copy of the state and the action. They may directly modify the draft state, and do not return any value. The object map of Handlers is passed into the createReducer function, which returns a redux reducer. Your reducer code now looks like this:

const handlers = {
  [SET_FAVORITE_CHIPS]: (draft, action) => {
    draft.favorite = action.payload;
  },
  [SET_CHIPS_FOR_SALE]: (draft, action) => {
    draft.forSale = action.payload;
  }
}

const reducer = createReducer(initialState, handlers);

In the background createReducer uses immer to create a mutable copy of the state.

Quick Start

1. Install using npm, yarn, pnmp, or whatever package manager you use:

   npm install redux-handlers
   yarn add redux-handlers
   pnmp install redux-handlers

2. Import createReducer into your reducers file and use to convert your handlers map object to a reducer:

   import createReducer from 'redux-reducer-handlers';
   
   const reducer = createReducer(initialState, handlers)