Node

Question 1

What is Node.JS?

Answer 1

A program that allows JavaScript to be run outside of a web browser

Question 2

What can Node.JS be used for?

Answer 2

Commonly used to build back ends for Web Applications, command-line programs, or other automation software developers wish to perform

Question 3

What is a REPL?

Answer 3

Read, Eval, Print loop —> also termed a ‘language shell’

Question 4

When was Node.JS created?

Answer 4

May 27, 2009 —> created by Ryan Dahl

Question 5

What backend languages have you heard of?

Answer 5

Python, Ruby, Java, PHP, C, C++, c# (.net), JavaScript (&Node)

Question 6

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

Answer 6

A global that provides information and control over the current node.JS process

Question 7

What is a ‘process’?

Answer 7

Any one program that your computer is running at a given time

Question 8

When you execute a file with node, you start a…

Answer 8

Process!

Question 9

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

Answer 9

It’s globally available, so you can just type ‘process’ (although it also can be required in)

Question 10

What data type does process.argv return in node.JS?

Answer 10

It returns an array containing command line args passed in when the process was launched

Question 11

What will process.argv[0] be?

Answer 11

The path to node’s executionable file

Question 12

What will process.argv[1] be?

Answer 12

The path to the JavaScript file being executed

Question 13

What will process.argv[2] onwards be?

Answer 13

Any command line arguments

Question 14

Every index in the argv array always is… (data type)

Answer 14

A string

Question 15

What is a JavaScript module?

Answer 15

A module is a single .JS file.

Question 16

All modules are wrapped in a…

Answer 16

Function

Question 17

What values are passed into a Node.JS module’s local scope via the wrapping function?

Answer 17

exports, require, module, __filename, __dirname

Question 18

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

Answer 18

Process & console objects (global, setTimeout, setInterval)

Question 19

What determines what is returned by .require(‘file-path’)?

Answer 19

Whatever is stored in the module.exports variable in the file specified.

Question 20

Will variables between files collide?

Answer 20

No —> because each file is wrapped in a function, they have their own unique scope

Question 21

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

Answer 21

It allows you to export code out from one module

Question 22

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

Answer 22

1. Set module.exports = ‘what-to-export’
2. Use the require keyword with the file path passed in as the argument

Question 23

What is the JavaScript Event Loop?

Answer 23

It allows JavaScript to run async events in a sequential order.

Question 24

What is different between ‘blocking’ and ‘non-blocking’ with respect to how code is executed?

Answer 24

Blocking code ‘blocks’ the call stack —> while it’s running, nothing else can happen. Non-blocking code doesn’t stay on the call stack forever, allowing other things to run while it does work.

Question 25

What does ‘single-threaded’ mean?

Answer 25

It can only run one thing at a time

Question 26

What is a directory?

Answer 26

A unique type of file that contains travel information to access files or other directories

Question 27

What is a relative file path?

Answer 27

The path to a file from where you are currently at

Question 28

What is an absolute file path?

Answer 28

The path to a file from the root directory

Question 29

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

Answer 29

The File system (fs) module

Question 30

The require function always takes what data type?

Answer 30

String! Either a file path for a file OR a module name for a module

Question 31

When using an absolute file path, instead of using a hard-coded path you can use…

Answer 31

The path module —> path.join(argument1, argument2)

Question 32

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

Answer 32

fs.writeFile( )

Question 33

Are file operations using the fs module synchronous or asynchronous?

Answer 33

Depends on the operation! Typically asynchronous. Tbh ignore the synchronous ones.

Question 34

What is npm?

Answer 34

The worlds largest software registry. Three components: website, CLI, and registry.

No longer called node package module —> used for more than just node.

Question 35

What is a package in npm?

Answer 35

Reusable bits of code —> a directory with one or more files in it with a package.json file

Question 36

How can you create a package.json with npm?

Answer 36

Run the command ‘npm init’ at the root directory of the package.

Adding —yes auto-fills the package.json file

Question 37

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

Answer 37

It’s a library (another package) your project (your package) requires to work properly. Using npm install ‘package’ will install the package as a dependency.

Question 38

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

Answer 38

That dependency is added to the node_modules folder along with all files related to that package in addition to all of its dependencies. It also adds and it under dependencies in package.json