redux-reducer

Even simpler reducers with 0 boilerplate

Installation

One of the following:

• npm i -S @commander-lol/redux-reducer
• yarn add @commander-lol/redux-reducer
• ied i -S @commander-lol/redux-reducer

Why?

redux-reducer strips out the common boilerplate used to determine what actions to take when a reducer is run, as well as allowing you to programmatically compose a reducer at runtime. It also handles the default case for you, saving potentially hours of bug hunting when you overlook it.

Usage

When you're writing reducers for Redux, you probably have something similar to the following:

const initialState = {
  dongles: {},
}

export default function myReducer(state = initialState, {type, ...action}) {
  switch(type) {
    case "ADD_DONGLE": {
      let { dongles } = state
      let { dongle } = action
      dongles = {
        ...dongles,
        [dongle.id]: dongle,
      }
      
      return {
        ...state,
        dongles,
      }
    }
    default: 
      return state
  }
}

And that's a pattern that will appear in pretty much every one of your reducers. Instead, using the redux-reducer library turns that into the following:

const reducer = require('@commander-lol/redux-reducer')

const initialState = {
  dongles: {},
}

export default reducer(initialState, {
  ADD_DONGLE: ({ dongles, ...state }, { dongle }) => {
    return {
      ...state,
      dongles: {
        ...dongles,
        [dongle.id] = dongle,
      },
    }
  }
})

API

The library exports a single function that returns a redux-compatible reducer function;

reducer(initial: Object, handlers: Map<string, Handler>)

Where initial is the initial router state and handlers is a string -> function map of action types to action reducers. Each handler is passed state and action as parameters, which correspond to the assigned reducer state and the current action and should return the new version of state after resolving the action. Simple as that.