Node.js

Question 1

What is Node.js?

Answer 1

• An asynchronous JavaScript runtime

- A program or set of libraries 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 any kind of automation that developers wish to perform
• It is primarily focused on creating simple, easy-to-build network clients and servers.
• Can write client application and server applications in Node

Question 3

What is a REPL?

Answer 3

• Stands for “Read-Eval-Print-Loop”

- It is reads single user inputs, executes/evaluates them, and returns/prints the result to the user

Question 4

When was Node.js created?

Answer 4

2009

Question 5

What back end languages have you heard of?

Answer 5

• Python
• Ruby on Rails
• Java
• PHP
• C++
• C#
• SQL
• Perl
• Go

Question 6

What is a computer process?

Answer 6

• The instance of a computer program that is being executed by one or many threads.
• It contains the program code and its activity.
• It is the actual execution of the computer program instructions.
• takes the program and runs it, starts asking for RAM

Question 7

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

Answer 7

hundreds

Question 8

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

Answer 8

• 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
• NEED to know HTTP
• client process sends http request to

Question 9

runtime

Answer 9

• when the program is executed

- language environment, how your program is executed by node.js

Question 10

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

Answer 10

The process object is a global that provides information about, and control over, the current Node.js process. As a global, it is always available to Node.js applications without using require().

Question 11

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

Answer 11

global process

Question 12

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

Answer 12

An array

Question 13

process.argv (property)

Answer 13

• Returns an array containing the command line arguments passed when the Node.js process was launched.
• First element: process.execPath. (See process.argv0 if access to the original value of argv[0] is needed. )
• Second element: the path to the JavaScript file being executed.
• The remaining elements will be any additional command line arguments.

Question 14

What are real world applications for using process.argv?

Answer 14

command line processes use own process.argv

Question 15

modular programming

Answer 15

• breaking up into chunks and having smaller pieces of functionality
• a software design technique that emphasizes separating the functionality of a program into independent, interchangeable modules, such that each contains everything necessary to execute only one aspect of the desired functionality.

Question 16

What is a JavaScript module?

Answer 16

a single .js file.

Question 17

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

Answer 17

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

Question 18

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

Answer 18

process

Class: Buffer

Question 19

CommonJS

Answer 19

a project with the goal to establish conventions on the module ecosystem for JavaScript outside of the web browser. 
 module specification is widely used today, in particular for server-side JavaScript programming with Node.js.

Question 20

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

Answer 20

to store one module’s properties and methods on the module.exports to be transferred to another module

Question 21

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

Answer 21

require function

Question 22

What is the JavaScript Event Loop?

Answer 22

The process in which JS monitors the stack and callback queue. If the stack is empty, it will push tasks (if any) from the task/callback queue onto the stack

Question 23

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

Answer 23

blocking: code that is executed synchronously, code that blocks the call stack and prevents the browser from doing anything else until the process is finished

non-blocking: code that is executed asynchronously, still allows the browser to do its thing in between executing of this async code

Question 24

What is a directory?

Answer 24

special type of file that holds information about more directories and files

Question 25

What is a relative file path?

Answer 25

path to a specific file from another file (not at the root)

Question 26

What is an absolute file path?

Answer 26

absolute path starts at the root of a file

Question 27

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

Answer 27

fs module

Question 28

fs.readFile(path[, options], callback)

Answer 28

• path | | | filename or file descriptor

- callback : err , data |

Question 29

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

Answer 29

fs.writeFile

Question 30

Are file operations using the fs module synchronous or asynchronous?

Answer 30

both!