10 ReactJS quizzes

#react #programming #quizz #javascript

If you want to import just the Component from the React library, what syntax do you use?

☑️ import React.Component from 'react'
☑️ import [ Component ] from 'react'
☑️ import Component from 'react'
✅ import { Component } from 'react'

If a function component should always render the

same way given the same props, what is a simple performance optimization available for it?

✅ Wrap it in the React.memo higher-order component.
☑️ Implement the useReducer Hook.
☑️ Implement the useMemo Hook.
☑️ Implement the shouldComponentUpdate lifecycle method.

How do you fix the syntax error that results from running this code?

const person =(firstName, lastName) => { first: firstName, last: lastName } console.log(person("Jill", "Wilson"))

✅ Wrap the object in parentheses.
☑️ Call the function from another file.
☑️ Add a return statement before the first curly brace.
☑️ Replace the object with an array.

If you see the following import in a file, what is being used for state management in the component?

import React, {useState} from 'react';

✅ React Hooks
☑️ stateful components
☑️ math
☑️ class components

Using object literal enhancement, you can put values back into an object. When you log person to the console, what is the output?

const name = 'Rachel'; const age = 31; const person = { name, age }; console.log(person);

☑️ {{name: "Rachel", age: 31}}
✅ {name: "Rachel", age: 31}
☑️ {person: "Rachel", person: 31}}
☑️ {person: {name: "Rachel", age: 31}}

What is the testing library most often associated with React?

☑️ Mocha
☑️ Chai
☑️ Sinon
✅ Jest

To get the first item from the array ("cooking") using array destructuring, how do you adjust this line?

const topics = ['cooking', 'art', 'history'];

☑️ const first = ["cooking", "art", "history"]
☑️ const [] = ["cooking", "art", "history"]
☑️ const [, first]["cooking", "art", "history"]
✅ const [first] = ["cooking", "art", "history"]