NodeJS

Question 1

What is NodeJS?

Answer 1

NodeJS is a Javascript runtime that works for backend programming

Question 2

NodeJS extends from an engine, what engine?

Answer 2

V8 Google engine, used to mainly in google chrome and NodeJs

Question 3

Which language is V8 written in?

Answer 3

written in C++, to support Javascript.

Question 4

How to execute Node from Cmd?

Answer 4

typing node

Question 5

requiring a library that deals with file i/o

Answer 5

const fs = require(‘fs’)

Question 6

creating a file synchronously with some content

Answer 6

fs.writeFileSync(‘filename.txt’, ‘filecontent’);

Question 7

One example of development that is not associated with developing for server-side with NodeJS

Answer 7

Dealing with local files to process Building of production versions, ReactJs uses node indirectly for that, creating utility scripts in general.

Question 8

What are the two ways of executing Node code?

Answer 8

by executing files (node (filename)) or REPL:

Read, Evaluate, Print, Loop, which is a way of executing code on the go in the command line, good playground.

Question 9

Module to help with path concatenations

Answer 9

path, path.resolve(path1, path2)

Question 10

The NodeJS event loop consists of 5 basic processes, the first step is

Answer 10

1. Execution of timer functions (setTimer, setInterval, etc);

Question 11

The NodeJS event loop consists of 5 basic processes, the second step is

Answer 11

2. Execute pending (non-timer) callbacks from previous loops, such as I/O related callbacks and other events

Question 12

The NodeJS event loop consists of 5 basic processes, the third step is

Answer 12

3. Fetch new (non-timer) Event callbacks such as new connections and try to execute them right away, Or defer them to be executed in the next loop (2nd step)

Question 13

The NodeJS event loop consists of 5 basic processes, the forth step is

Answer 13

4. execute setImediate() callbacks, these are callbacks that execute always in the same loop, but always after all previous steps

Question 14

The NodeJS event loop consists of 5 basic processes, the last step is

Answer 14

5. Execute all ‘close’ event callbacks

Question 15

What can happen when a long operation has to be executed by NodeJs?

Answer 15

It transfer the operation to the poll workers, which is carried with the work of deferring the process to another thread, the workers make sure this process happens automatically.

Question 16

How to serve a file with the absolute path and the .html file to a user?

Answer 16

const path = require('path');
res.sendFile(path.join(\_\_dirname, '/view/page.html');

Question 17

What does express.use(‘/admin’, adminRouter); does?

Answer 17

appends the path ‘/admin’ to all routes inside adminRouter.

Question 18

Difference between path.resolve() vs path.join()

Answer 18

path. resolve is absolute, gets the root directory all the way from C:\
path. join starts with ‘./’, is relative, plus it converts the path in a way that works for both linux and windows.

Question 19

consider: path.join(__dirname, ‘..’, ‘views’, ‘index.html’);

why is using ‘..’ instead of ‘../’ useful?

Answer 19

Because it goes up 1 directory level while preserving compatibility between different OS’s paths structure

Question 20

what does path.dirname(string dir) returns?

Answer 20

returns the current already formated path, good for modularization and helper functions.

Question 21

how to retrieve the application main entry point defined in package.json with the ‘process’ global var?

Answer 21

proccess.mainModule.filename

Question 22

express().set() and express().get() does

Answer 22

sets a global variable that express may or may not understand, like: app.set(‘var_name’, ‘value’)

express.get(‘var_name’) will return it globally.

Question 23

setting a templating engine with express

Answer 23

express().set(‘view engine’, (engine));
‘view engine’ is a reserved express global configuration option.

(engine) configures one of the templating engines that have built-in compatibility with express, such as pug, ejs.
(optional) telling express where is the root folder of the views:

express().set(‘views’, ‘(folder_path)’) // Default path location is ‘views’.

Question 24

method to build on-the-fly and send to the user a dynamically outputted html page

Answer 24

res.render();