Questions on module titled: JavaScript

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1. What is a callback function in JavaScript?

A function passed into another function as an argument to be executed later

A function that calls itself

A function that can be used as a callback

A function that returns a callback

2. Which of the following is a JavaScript package manager?

npm

yaml

pip

apt

3. What is a promise in JavaScript?

A synchronous operation

An object representing the eventual completion or failure of an asynchronous operation

A function that always resolves

A function that never resolves

4. What is Express.js?

A minimal and flexible Node.js web application framework

A JavaScript runtime

A library for building user interfaces

A tool for transpiling ES6 code to ES5

5. What is the mysql2 library used for in Node.js?

To make MySQL queries in Node.js

To create servers

To create user interfaces

To transpile ES6 code to ES5

6. Which keyword is used to define an asynchronous function in JavaScript?

await

promise

async

defer

7. What is the purpose of the 'package.json' file in an npm project?

To store the project’s build files

To list all installed packages globally

To configure the node environment

To define the metadata of the project and manage dependencies

8. What is the purpose of the .then() method in JavaScript Promises?

It returns a Promise and takes two arguments: callback functions for the success and failure cases of the Promise

It is used to pause the execution of a function

It is used to handle errors in asynchronous operations

It is used to execute a function once the document is ready

9. What is the purpose of the .catch() method in JavaScript Promises?

It is used to pause the execution of a function

It is used to execute a function once the document is ready

It is used to handle the success case of a Promise

It is used to handle the rejection of a Promise

10. What does the 'spread operator' do in JavaScript?

Copies an object deeply

Expands an array or object into individual elements

Combines two arrays into one

Creates a new instance of an object

11. Which command initializes a new npm project?

npm start

npm create

npm init

npm new

12. What does 'npm start' do?

Starts a new npm project

Installs dependencies

Starts a Node.js server

Runs the startup script specified in package.json

13. What is the purpose of the this keyword in JavaScript?

It refers to the global object

It refers to the object that is executing the current function

It refers to the function itself

It refers to the parent object