SERVER SIDE BACKEND

Question 1

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

Answer 1

It creates a module that can be imported into another file

Question 2

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

Answer 2

const, var , or let followed by a variable name then assign it a require(directory/filename)

SYNTAX: const add = require(./add) 
THE .js can be ommitted as it is implied.

Question 3

What is the JavaScript Event Loop?

Answer 3

It pushes code that is in the callback Queue onto the call stack

Question 4

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

Answer 4

Blocking is code that must finish before anything else can be done and non-blocking are code that is run immediately onto the stack; Javascript can make blocking into non-blocking by putting it to the side

Question 5

Directory

Answer 5

a folder that holds file

Question 6

relative file path

Answer 6

it is within the computer starting from current directory, relative to where you are from

Question 7

absolute file path

Answer 7

it states the whole path from the root to where it is in the folder

Question 8

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

Answer 8

it is fs module

can use require(‘fs);

Question 9

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

Answer 9

fs.writefile

Question 10

Are file operations using the fs module synchronous or asynchronous?

Answer 10

asynchronous unless stated as synch in the method

Question 11

What is a client? What is a server?

Answer 11

The client is the one that requests information while the server hosts and wait for request to give the information

Question 12

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 12

It uses the GET method

Question 13

What is on the first line of an HTTP request message?

What is on the first line of an HTTP response message?

Answer 13

A start-line describing if request/response is successful or failed
FOR REquESt: a http method (get, put , post) and the request target usually an absolute path
for Responses: Status Line (protocol version, status code, status text_

Question 14

What are HTTP headers? Is a body required for a valid HTTP message?

Answer 14

Headers: case insentiive string followed by a colon and a value depending on the type of header, General (via), response(vary and accept-ranges), and representation headers(content-type)
Bodies are not neccessary

Question 15

What is NPM? What is a package?

Answer 15

It is a package manager, that is open sourced where people can send code or technologies and modify or use that code

A package is a building block that solves one problem and solves it well, a reusable code that can be implemented in custom projects
a Package is:
a) a folder containing a program described by a package.json file
b) a gzipped tarball containing (a)
c) a url that resolves to (b)
d) a @ that is published on the registry (see registry) with (c)
e) a @ (see npm dist-tag) that points to (d)
f) a that has a “latest” tag satisfying (e)
g) a that resolves to (a)

Question 16

How can you create a package.json with npm?

Answer 16

navigate to the root path and then run : npm init

Question 17

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

Answer 17

Packages that it depends on whether it is a package lock, shirnkwrap file or yarn lock, the installation of dependencies will be driven by that npm install

Question 18

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

Answer 18

It creates a folder in the node modules directory and add to the dependencies

Question 19

How do you add express to your package dependencies?

Answer 19

npm install express

require(‘express’)

Question 20

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

Answer 20

listen method
const app =express();
app.listen(3000, () =. {
(code here)
});

Question 21

How do you mount a middleware with an Express application?

Answer 21

app.use() the first parameter is the path where the middleware function executes when the base of the req path matches path

Question 22

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

Answer 22

(req, res) request and response; (request object is passed in)

Question 23

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

Answer 23

application/json which runs UTF encoding

Question 24

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

Answer 24

The significance is that it will determine what the response will be, it by letting the server know what to do do

Question 25

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

Answer 25

It is so that the app will be able to read and parse incoming requests with JSON loads Returns middleware that only parses JSON and only looks at requests where the Content-Type header matches the type option

Question 26

What does express.static() return?

Answer 26

(it returns a function that

does HTTP 404 Not Found if the file is not there otherwise it returns your file.

Question 27

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

Answer 27

The directory name of the current module, it is the same path as (path.dirname(__filename));

Question 28

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

Answer 28

Joins all given path segments together

EXample SetUP:
const joinedPath = path.join(\_\_dirname, 'public');
app.use(express.static(joinedPath));