Aurélie Bayre

why JSX?

can you have more than one root dom nodes?

How do you render an element into the dom?

Are React elements mutable?

There are two ways of defining a component: as a function and as a ...

What is the advantage of a class component over a functional component?

How do you add local state to a class?

why are lifecycle hooks important?

Does redux work only with react?

Core concepts: actions reducers

what's an action for redux?

What's the purpose of a reducer?

what are the 2 params passed to a reducer?

what are the advantages of a single store?

How is Redux different from Flux?

advantage of immutability in Redux?

Redux architecture revolves around a strict unidirectional data flow.

Data lifecycle: 1. You call store.dispatch(action) 2. Redux store calls the reducer function 3. combine output of multiple reducer into on single state tree 4. Redux store returns the complete state tree (returned by the root reducer)

Ex with a combineReducers() function todos(state = [], action) { // Somehow calculate it... return nextState } ​ function visibleTodoFilter(state = 'SHOW_ALL', action) { // Somehow calculate it... return nextState } ​ let todoApp = combineReducers({ todos, visibleTodoFilter })

React bindings for Redux embrace the idea of separating presentational and container components.

Container Components: How things work (data fetching, state updates) Dispatch Redux actions Are usually generated by React Redux

Presentational Components How things look (markup, styles) Invoke callbacks from props to change data Are written by hand

You could write a container component by hand, but we suggest instead generating container components with the React Redux library's connect() function, which provides many useful optimizations to prevent unnecessary re-renders.

To use connect(), you need to define a special function called mapStateToProps that tells how to transform the current Redux store state into the props you want to pass to a presentational component you are wrapping.

In addition to reading the state, container components can dispatch actions. In a similar fashion, you can define a function called mapDispatchToProps() that receives the dispatch() method and returns callback props that you want to inject into the presentational component.

Connecting react and redux: import { connect } from 'react-redux' ​ const VisibleTodoList = connect( mapStateToProps, mapDispatchToProps )(TodoList) ​ export default VisibleTodoList

Redux component <Provider> : is used to magically make the store available to all container components in the application without passing it explicitly. You only need to use it once when you render the root component:

How do you use <provider> ?