Node.js

Question 1

What is a CLI?

Answer 1

Command Line Interface, processes commands to a computer program in the form of lines of text

Question 2

What is a GUI?

Answer 2

Graphical user interface, a form of user interface that allows user to interact with electronic devices through graphical icons and audio indicators

Question 3

Give at least one use case for each of the commands listed in this exercise.

man
cat
ls
pwd
echo
touch
mkdir
mv
rm
cp

Answer 3

man - displays content of the manual, and also specific commands
cat - prints text, and also joins text files together
ls - view contents of a directory
pwd - shows location of current directory
echo - prints text that you write after the echo command
touch - creates files
mkdir - creates directories
mv - renames or moves files (source … target)
rm - removes files and directories (need -r)
cp - copies files and directories

Question 4

What are the three virtues of a great programmer?

Answer 4

• LAZINESS: Great efforts to reduce overall energy expenditure. Labor saving code that others will value, in addition to it begin well documented.
• IMPATIENCE: Write programs that you anticipate need for.
• HUBRIS: Write and maintain programs and other people won’t say bad things about.

Question 5

What is Node.js?

Answer 5

Node.js is a set of libraries for JavaScript which allows it to be used outside of the browser.

Question 6

What can Node.js be used for?

Answer 6

• Back end for web pages
• Running JS outside of a browser
• Realtime applications
• Collaboration tools

Question 7

What is a REPL?

Answer 7

Simple interactive programming environment. For example, the browser console.

Question 8

When was Node.js created?

Answer 8

2009, by Ryan Dahl

Question 9

What back end languages have you heard of?

Answer 9

• JavaScript (Only one with event loop)
• PHP
• Ruby
• Python
• SQL
• Elixir
• C++
• Go
• C#
• F#
• VBA
• Clojure
• C
• Julia
• Haskell
• Pascal
• Rust
• Lisp
• Perl
• TypeScript
• Objective-C
• Swift
• Kotlin
• Scala

Question 10

What is a computer process?

Answer 10

A computer process is an instance of a program being executed by one or more threads, containing program code and activity.

Question 11

Roughly how many computer processes are running on your host operating system (Task Manager or Activity Monitor)?

Answer 11

300+

Question 12

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

Answer 12

Full stack programs server and database, communicating with each other.

Question 13

What is theprocessobject in a Node.js program?

Answer 13

A process object is a global object that provides information about and control over the current Node.js process

Question 14

How do you access theprocessobject in a Node.js program?

Answer 14

Process is global so it may be accessed without use of “require()”m but it may also be explicitly accessed with require

Question 15

What is the data type ofprocess.argvin Node.js?

Answer 15

Process.argv is an array of strings

Question 16

What is a JavaScript module?

Answer 16

A JavaScript file

Question 17

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

Answer 17

• __dirname
• __filename
• Require
• Exports
• Module

Question 18

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

Answer 18

• Console
• setInterval
• setTimeout

Question 19

What is the purpose ofmodule.exportsin a Node.js module?

Answer 19

To allow your multiple modules to be used together and share functionality

Question 20

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

Answer 20

Using the require function, with the module’s file path as the argument.

e.g. const add = require(‘./add’);

Question 21

What is the JavaScript Event Loop?

Answer 21

Event loop checks whether or not the call stack is empty. If it is empty, new functions are added from the event queue.

Question 22

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

Answer 22

• Blocking occurs when call stack is full, currently occupying the call stack
• Nonblocking is when tasks are popped off the call stack

Question 23

What is a directory?

Answer 23

File that contains files

Question 24

What is a relative file path?

Answer 24

A relative file path starts at the current directory

Can start with:

• ./ or nothing (for current directory)
• ../ (for parent directory)

Question 25

What is an absolute file path?

Answer 25

A file path that starts at the root directory

/home/dev/repos/c0821-code-solutions

Question 26

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

Answer 26

fs module (file system)

Question 27

What method is available in the Node.jsfsmodule for writing data to a file?

Answer 27

fs.writeFile()

Question 28

Are file operations using thefsmodule synchronous or asynchronous?

Answer 28

Both types are available in the Node.js documentation

Question 29

What is NPM?

Answer 29

• NPM docs
• NPM client, used to publish reusable-code
• NPM Registry, database of info about packages people are sharing

Question 30

What is a package?

Answer 30

• Directory with one or more file within it

- Has to have package.json file

Question 31

How can you create apackage.jsonwithnpm?

Answer 31

npm init -y

Question 32

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

Answer 32

• A dependency is a package that you can add to your package.json file
• npm install ‘insertpackage’

Question 33

What happens when you add a dependency to a package withnpm?

Answer 33

• Shows as a dependency on your package.json file

- Installs package inside of node_modules