This lesson is just a helper to make the process of writing reducers use less boilerplate code. This step briefly introduces to a world of helpers in writing Redux code.

Take a peek at useful helpers and middleware created by community are:

immer: https://github.com/mweststrate/immer - improves ergonomics of working with immutables by introducing the concept of mutating a draft
redux-starter-kit: https://github.com/reduxjs/redux-starter-kit - help address common concerns of Redux in boilerplate and complexity

Exercise

open up exercise/src/reducers/index.ts
implement the filterReducer function with a switch / case statement - it is contrived to have a switch case for ONE condition, but serves to be a good exercise here
replace the export reducer function with the help of the combineReducer() function from redux

Bonus Exercise

The Redux team came up with redux-starter-kit to address a lot of boilerplate concerns. They also embed the immer library to make it nicer to write reducer functions. So, let's try out immer! Look at this example: https://github.com/mweststrate/immer#reducer-example

import immer into the exercise/src/reducers/pureFunction.ts file
replace the implementation of the pure functions with the help of immer's produce()
run npm test in the root folder to see if it still works!
look at the web app to make sure it still works!