React

Question 1

What is React?

Answer 1

Framework to create interactive UIs in a web browser

Question 2

What is a React element?

Answer 2

a plain object describing a component instance or DOM node and its desired properties., react component

Question 3

How do you mount a React element to the DOM?

Answer 3

Render method
DOMElementHere.render(elementhere)

Question 4

What is JSX?

Answer 4

a syntax extension for JavaScript that lets you write HTML-like markup inside a JavaScript file

Question 5

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

Answer 5

React elements will be undefined

Question 6

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

Answer 6

Babel reads the JSX and converts to JavaScript while webpack loads them module to read it.
plugin for babel loader

Using the appropriate converter with the proper babel loader

Question 7

What is a React component?

Answer 7

JavaScript function that you can use markup with
reusuable code such as js functions

Question 8

How do you define a function component in React?

Answer 8

Export default function functName() {
Return (

<div>
)
}

name is wit capitalized first letter and return JSX
</div>

Question 9

How do you mount a component to the DOM?

Answer 9

Mount means render so that it displays, using render method

Question 10

What are props in React?

Answer 10

standardized way to pass arguments to a function

Question 11

How do you pass props to a component?

Answer 11

inside angle brackets, property = value

Question 12

How do you write JavaScript expressions in JSX?

Answer 12

in curly brackets

Question 13

What is the purpose of state in React?

Answer 13

re-renders the component to the browser

Question 14

What is a React Effect?

Answer 14

Function that will execute after the render

Question 15

When should you use an Effect and when should you not use an Effect?

Answer 15

Effects are typically used to “step out” of your React code and synchronize with some external system

Question 16

When do Effects run?

Answer 16

After it mounts/render, when a dependency changes

Question 17

What function is used to declare an Effect?

Answer 17

useEffect(callback, dependencies);

Question 18

What are Effect dependencies and how do you declare them?

Answer 18

tell React to skip unnecessarily re-running the Effect by specifying an array of dependencies, In an array

Question 19

How do you clean up from an Effect?

Answer 19

if return a funct from useEffect, , clear up the interval

Question 20

Why would you want to clean up from an Effect?

Answer 20

returning a function from effect callback

Question 21

When does the clean up function run?

Answer 21

before effect runs next time, and during unmount