Basic over view

Question 1

What are Components ?

Answer 1

Basically JavaScript classes with a state and a render

Question 2

What does a class look like

Answer 2

Class Name { state: {}; render () {} }

Question 3

What is the render( ) { }

Answer 3

Method to a react element

Question 4

What is a react element

Answer 4

a plan Java script obj that maps to DOM element

Question 5

How many DOM are there

Answer 5

Virtual DOM and real Dom, children must be kept in order

Question 6

Where is the root container held

Answer 6

In the index.html file

Question 7

What extends app.js ?

Answer 7

extends by Component at built in Java Script class

Question 8

How to write app class

Answer 8

Class App extends Component {render() { returns JSX;
}}

Question 9

What is babel

Answer 9

A modern java script compiler

Question 10

how to make a bisc react element

Answer 10

const element = <> </>;

Question 11

Import React from ‘react’; which is the module and obj

Answer 11

React obj ‘react’ is module

Question 12

2 obj that must be imported

Answer 12

React
ReactDOM

Question 13

What is hot module reloading, t

Answer 13

This is where react uses babbel to to compile JavaScript objects directly on the fly

Question 14

What are the two arguments in react Dom

Answer 14

Element, document get Element by ID

Question 15

Shortcut for import react component

Answer 15

I MRC

Question 16

Shortcut for class components

Answer 16

CC

Question 17

How to rap to html elements togeather

Answer 17

React.Fragment

Question 18

State is an object and what does it hold ?

Answer 18

properties

Question 19

What is an expression

Answer 19

Javascript the expression references the state or function object using this keyword

Question 20

Example of object destructuring

Answer 20

const { count } = this.state;

Question 21

How to write if for state count

Answer 21

return count === 0 ? “Zero” : count;

Question 22

How to render a list of tags [ ]

Answer 22

this.state.tags.map(
(tag) => (<li key={tag}>{tag}</li>

Question 23

What is setting attributes

Answer 23

className = / styles

Question 24

If && operator is applied second True is printed out

Answer 24

True && “ hi”

Question 25

When is undefined declared as an error ?

Answer 25

When " this " is outside of an object. this refers to the Method inside an object.

Question 26

Why write an arrow function

Answer 26

Due to event handlers are out of scope

Question 27

What does an arrow function look like

Answer 27

handleIncreament = () => { console.log("clicked"); this.setState({ count: this.state.count + 1 }); };

Question 28

How to use map function

Answer 28

[ ].map to each obj => ()

Question 29

What does every react component have

Answer 29

props

Question 30

Components can or cannot modify own state?

Answer 30

The component that owns a piece of the state should be the one modifying it

Question 31

What is the difference between state and properties ?

Answer 31

state is local to that component, props are not.

Question 32

how to make a button

Answer 32

button.btn.btn-danger.btn-sm.m-2