Code 401: Class 37 - Redux - Combined Reducers

Questions

Why choose Redux instead of the Context API for global state? The jury seems to be out on this question, many examples online point to either one as being the better choice or in some cases they should be used together. Context appears to be the better option when dealing the static data like theme selection while Redux is often better for storing global state data that is more dynamic.
What is the purpose of a reducer? A function that determines the changes to an applications state, uses the action to determine the change
What does an action contain? Actions are the only way to updated data in the store. Must include a type and can pass a payload containing data
Why do we need to copy the state in a reducer? Data in the store is immutable, so to make changes a copy must be made in the reducer so that it can be changed

Immutable state state the cannot be changed
Time travel in redux Redux dev tools records dispatched actions and the state of the Redux, possible to travel back in time to view previous app state without reloading
Action Creator The means by which state is changed in a Redux store
Reducer Function that determines changes to an application’s state
Dispatch a method on Redux store that is the only way to update the state. Call store.dispatch() and pass in an action object

import {combineReducers, createStore } from 'redux';
Example reducer: const userReducer = (state={}, action) => { return state };
Example combineReducer example: const reducers = combineReducers({user: userReducer, tweets: tweetReducer})

Reducers passed to combineReducers must satisfy the following:
- any action that is not recognized, must return state that was given as first argument
- must never return undefined
- if state given to it is undefined, must return initial state for the specific reducer