Node.js

Question 1

What is Node.js?

Answer 1

Program that allows JavaScript to run outside of a web-browser

Question 2

What can Node.js be used for?

Answer 2

• Build back ends for web apps
• Command-line programs
• Any kind of automation that developers wish to perform

Question 3

What is a REPL?

Answer 3

o Read-eval-print loop
o Interactive programming environment that takes single user inputs and executes them to return the result to the user (executed piecewise)

For example, the browser console

Question 4

When was Node.js created?

Answer 4

2009

Question 5

Back-end languages:

Answer 5

JavaScript
Java
Python
PHP
Ruby
Go
C++
C# (runs in .NET which is a framework)

Question 6

What is a computer process?

Answer 6

Instance of a program running in a computer

Question 7

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

Answer 7

Because full stack web applications require multiple processes to work together concurrently for it to be useable (multiple processes have to be up and running to properly deal with the app’s clients, servers and databases)

Question 8

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

Answer 8

Global object that provides information about/control over the current Node.js process

Question 9

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

Answer 9

process

Question 10

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

Answer 10

Array of strings

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

o	exports
o	require 
o	module 
o	\_\_filename
o	\_\_dirname

Question 13

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

Answer 13

o	console
o	process
o	Object
o	Undefined
o	global

Question 14

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

Question 15

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

Answer 15

require(‘./filename’)

Question 16

What is the JavaScript Event Loop?

Answer 16

How asynchronous callbacks are put back into the call stack when the call stack is clear

Question 17

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

Answer 17

o Blocking = Stack is occupied and prevents other code from running (like for-loops)
o Non-blocking = Stack is clear and event loop can occur

Question 18

What is a directory?

Answer 18

o Path to where the file is located

o Specific type of file that lists other files

Question 19

What is a relative file path?

Answer 19

A path to a file starting from the current directory

Question 20

What is an absolute file path?

Answer 20

A path to a file starting from the root (for windows, from the drive name)

Question 21

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

Answer 21

fs (file system)

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

Both

Question 24

What is npm?

Answer 24

Makes it easier for javascript developers to share the code they have created to solve particular problems

o stands for node package manager
o Made of 3 parts: Website, CLI and registry

Question 25

What is a package?

Answer 25

File or directory that is described by a package.json file

Question 26

How can you create a package.json with npm?

Answer 26

npm init –yes

Question 27

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

Answer 27

a package you download to run your program; the package should generally have code to implement in your own code

o A npm package installed using npm install
o npm install

Question 28

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

Answer 28

A new directory of the package gets created within the current directory

Question 29

How do you add express to your package dependencies?

Answer 29

npm install express

Question 30

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

Answer 30

.listen( )

Question 31

How do you mount a middleware with an Express application?

Answer 31

.use( )

Question 32

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

Answer 32

req

res

Question 33

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

Answer 33

application/json

Question 34

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

Answer 34

o It’s used to recognize incoming requests as JSON object

o To parse incoming request bodies

Question 35

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

Answer 35

o It allows us to express our intent – it’s just a string (does not have any special functions or actions)

o Helps capture the value we want to pass to perform a certain action

Note: There is no intrinsic meaning in an http request method

Question 36

What does express.static() return?

Answer 36

Return a middleware function that shows the path to a directory so its contents can become publicly accessible

Question 37

What is the local __dirname variable in a Node.js module?

Answer 37

Absolute path to a directory containing the current module

Question 38

What does the join() method of Node’s path module do?

Answer 38

Joins strings together to create a path to a directory