Node

Question 1

What is Node.js?

Answer 1

a program that allows JavaScript to be run outside of a web browser. Node.js is powered by V8; the same JavaScript engine in the Google Chrome browser. It is free, open-source software and its source code is available on GitHub.

Question 2

What can Node.js be used for?

Answer 2

It is commonly used to build scalable back ends for Web applications, command-line programs, or any kind of automation that developers wish to perform.

Question 3

What is a REPL?

Answer 3

A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise

Question 4

When was Node.js created?

Answer 4

May 27, 2009

Question 5

What back end languages have you heard of?

Answer 5

Node.js, PHP, Ruby, Python, Java

Question 6

What is a computer process?

Answer 6

the instance of a computer program that is being executed by one or many threads.

Question 7

Why should a full stack Web developer know that computer processes exist?

Answer 7

Full stack Web development is based on making multiple processes work together to form one application, so having at least a cursory awareness of computer processes is necessary. This will be extremely important when learning about applications made of multiple components, such as clients, servers, and databases.

Question 8

What is the process object in a Node.js program?

Answer 8

a global that provides information about, and control over, the current Node.js process.

Question 9

How do you access the process object in a Node.js program?

Answer 9

You can access it directly as it is a global object which means it is available to all Node.js applications

Question 10

What is the data type of process.argv in Node.js?

Answer 10

object

Question 11

What is a JavaScript module?

Answer 11

A single .js file

Question 12

What values are passed into a Node.js module’s local scope?

Answer 12

\_\_dirname 
\_\_filename
exports
module
require(id)

Question 13

Give two examples of truly global variables in a Node.js program.

Answer 13

AbortSignal

clearImmediate(immediateObject)

Question 14

What is the purpose of module.exports in a Node.js module?

Answer 14

To allow a module to export functions or variables in which another module can import it through require() in Node.js

Question 15

How do you import functionality into a Node.js module from another Node.js module?

Answer 15

You export the functionality you need by assigning the value of the functionality to the export object. You then import the functionality by assigning the return of the require function to a local variable in your destination module.

Question 16

What is the JavaScript Event Loop?

Answer 16

one of the four major concepts that sets JavaScript apart from many other languages. The order is a callback function is added to the stack but is then popped off and sent to the web API. It is then sent to the event queue when it will wait to be called. Once the call stack is empty, the first item in the event queue is pushed to the stack and execute.

Question 17

What is different between “blocking” and “non-blocking” with respect to how code is executed?

Answer 17

Blocking is when the code has to wait on a function to execute fully first before the rest of the code can run. Non-blocking is when the the function is sent to another thread so the code can continue running without waiting

Question 18

What is a directory?

Answer 18

AKA folders. It allow the user to group files into separate collections

Question 19

What is a relative file path?

Answer 19

The path to a specific file relative to the current directory

Question 20

What is an absolute file path?

Answer 20

The path to a specific file from the root directory

Question 21

What module does Node.js include for manipulating the file system?

Answer 21

File System module

Question 22

What method is available in the Node.js fs module for writing data to a file?

Answer 22

writeFile

Question 23

Are file operations using the fs module synchronous or asynchronous?

Answer 23

asynchronous

Question 24

What are default params?

Answer 24

When defining a function, you can set a parameter to use a default value in case if the function is called without an argument.

Ex: function square(a=6, b) {
random code
}

Question 25

What is a spread in function calls?

Answer 25

It expands an iterable (array, string, etc) into a list of arguments

Ex:
const nums = [1, 2, 3];
Math.max(…nums);
// This returns 3

Question 26

What is a spread in array literals?

Answer 26

It creates a new array using an existing array. Spreads the elements from one array into a new array.

Ex:
const nums1 = [1, 2, 3];
const nums2 = [a, b, c];
const nums3 = [...nums1, nums2];
//nums3 = [1, 2, 3, a, b, c]

Question 27

What is a spread in Javascript?

Answer 27

The spread syntax ( … ) allows an iterable, such as arrays or strings, to be expanded in usage as arguments for function calls, or elements for arrays

Question 28

What is a spread in object literals?

Answer 28

It copies properties from one object into another object.

Ex:
const feline = { legs: 4, family: 'Felidae' };
const lion = { ...feline, genus: 'Panthera' };
//lion = {legs: 4, family: 'Felidae', genus: 'Pantera' };

Question 29

What are rest params?

Answer 29

It collects all remaining arguments into an actual array

Question 30

What is NPM?

Answer 30

npm is the world’s largest software registry. Open source developers from every continent use npm to share and borrow packages, and many organizations use npm to manage private development as well.

Question 31

What is a package?

Answer 31

bits of reusable code from the npm repository

Question 32

How can you create a package.json with npm?

Answer 32

npm init –yes

Question 33

What is a dependency and how to you add one to a package?

Answer 33

A dependency is another package that your package needs in order to work.

You add one by using the npm install command in Node.

Question 34

What happens when you add a dependency to a package with npm?

Answer 34

The package.json file is updated to include the dependency and a node_modules directory is added with the dependency package installed

Question 35

How do you add express to your package dependencies?

Answer 35

Install it through npm ie npm install express

Question 36

What Express application method starts the server and binds it to a network PORT?

Answer 36

the listen method ie app.listen

Question 37

How does array destructuring work?

Answer 37

const score = [10, 8, 5, 4, 1]
const [gold, silver, bronze] = scores;

Question 38

How does object destructuring work?

Answer 38

const runner {
first: "Eliud",
last: "Kipchoge",
country: "Kenya",
title: "Elder of the Order of the Golden Heart of Kenya"
}
const {first, last, country } = runner;

const {title: otherName} = runner; // this destructures the title property from the object but assigns it to a variable named otherName ie this allows us to rename the variables

//NOTE: Default values can be assigned to variables if there isn’t a corresponding property from the object

first; //”Eliud”
last; //”Kipchoge”
country; //”Kenya”

Question 39

How does param destructuring work?

Answer 39

const person1 = {
firstName: 'Jimmy',
lastName: 'Smith',
age: 25
}

function fullName ( { firstName, lastName } ) {
 return ${firstName} ${lastName};
}

Question 40

What is a client?

Answer 40

A service requester like a browser

Question 41

What is a server?

Answer 41

Provider of resource or service

Question 42

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 42

GET

Question 43

What is on the first line of an HTTP request message?

Answer 43

A start-line describing the requests to be implemented,

Question 44

What is on the first line of an HTTP response message?

Answer 44

A start-line declaring the status of a request on whether if it was successful or a failure

Question 45

What are HTTP headers?

Answer 45

Information in an HTTP message specifying the request, or describing the body included in the message.

Question 46

Is a body required for a valid HTTP message?

Answer 46

No

Question 47

How do you mount a middleware with an Express application?

Answer 47

Bind the middleware by using the app.use() and app.METHOD() functions

Question 48

Which objects does an Express application pass to your middleware to manage the request/response lifecycle of the server?

Answer 48

the request object, the response object, and the next middleware function of the cycle

Question 49

What is the appropriate Content-Type header for HTTP messages that contain JSON in their bodies?

Answer 49

application/json

Question 50

What does the express.json() middleware do and when would you need it?

Answer 50

It returns middleware that only parses incoming requests with JSON payloads. This allows the app to already have JSON data that has already been parsed to use.

Question 51

What is the significance of an HTTP request’s method?

Answer 51

It gives the app instruction on what the user’s request wants