react

Question 1

what is react

Answer 1

react is a javascript framework for interactive UI

Question 2

What is a React element?

Answer 2

an element made in react that returns an html element

Question 3

How do you mount a React element to the DOM?

Answer 3

ReactDOM.createRoot( queried element )

Question 4

What is JSX?

Answer 4

syntax extension of javascript, produces react elements

Question 5

Why must the React object be imported when authoring JSX in a module?

Answer 5

jsx creates react elements so you need the react object to read the jsx

Question 6

How can you make Webpack and Babel work together to convert JSX into valid JavaScript?

Answer 6

babel loader

Question 7

What is a React component?

Answer 7

basically a javascript function that makes react elements

Question 7

What is a React component?

Answer 7

basically a javascript function that makes react elements

Question 8

How do you define a function component in React?

Answer 8

function definition like javascript that returns a react object

Question 9

How do you mount a component to the DOM?

Answer 9

root.render(element)

Question 10

What are props in React?

Answer 10

properties, javascript expressions

Question 11

How do you pass props to a component?

Answer 11

as a react function attribute

Question 12

How do you write JavaScript expressions in JSX?

Answer 12

inside { } curly braces

Question 13

How do you create “class” component in React?

Answer 13

class ClassName extends React.Components {

}

Question 14

How do you access props in a class component?

Answer 14

this.props.property

Question 15

What is the purpose of state in React?

Answer 15

keep track of a certain state over time of a component

Question 16

How to you pass an event handler to a React element?

Answer 16

prop attribute = { event handler }

Question 17

What are controlled components?

Answer 17

react element whose value is controlled by react

value of the element is stored in a state

Question 18

What two props must you pass to an input for it to be “controlled”?

Answer 18

value and onChange

Question 19

What Array method is commonly used to create a list of React elements?
What is the best value to use as a “key” prop when rendering lists?

Answer 19

Array.map( )

an id value

Question 20

When does React call a component’s componentDidMount method?

Answer 20

at definition time

after the first sucesssufl render

Question 21

Name three React.Component lifecycle methods.

Answer 21

componentDIdMount / unmount
constructor
render
didupdate

Question 22

How do you pass data to a child component?

Answer 22

props