React

Question 1

how to define a html/css class in react

Answer 1

className=”string”;

className={ expression }

Question 2

basic render function?

Answer 2

return (

<div></div>

);

Question 3

import react and hooks

Answer 3

import React, {useEffect, useState, createRef, etc.. } from “react”;

Question 4

set up a basic state variable and setter

Answer 4

const [varName, setVarName] = useState();

Question 5

set a default state when setting up a state variable

Answer 5

const [varName, setVarName] = useState(‘default val’);

Question 6

update a state variable using the setter

Answer 6

setVarName(‘new value’);

Question 7

set up a useEffect handler function

Answer 7

useEffect(() => {
actionHandler();
});
//or: },[list, of, functions, to, watch]
use [] so it only activates on first mount

Question 8

create a Ref to a dom element

functionally

Answer 8

let textInput = useRef(null);

using:
{
props.setEmail(textInput.current.value)
}}

in render:
…
ref={textInput} />

Question 9

what does ‘useEffect return’ equal?

Answer 9

useEffect return is mostly equal to componentWillUnmount