npm

Question 1

What is npm?

Answer 1

npm(Node Package Manager) is the world’s largest software registry. Open source developers from every continent use npm to share and borrow packages, and many organizations use npm to manage private development as well.

npm consists of three distinct components:

1. The Website: Use the website to discover packages, set up profiles, and manage other aspects of your npm experience. For example, you can set up organizations to manage access to public or private packages.
2. The Command Line Interface (CLI): The CLI runs from a terminal, and is how most developers interact with npm.
3. The Registry: The registry is a large public database of JavaScript software and the meta-information surrounding it.

Question 2

What is a package?

Answer 2

A directory with one or more files of reusable code in it, and also has a file called package.json with some meta-data about this package.

If it has package.json, it is a package.

Question 3

How can you create a package.json with npm?

Answer 3

~/repos/c0621-code-solutions/npm-intro (npm-intro)

λ npm init –yes

Question 4

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

Answer 4

A dependency is another package that your package needs in order to work.

You can add one to a package by:
Ex:
npm install jquery

Question 5

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

Answer 5

It downloads the package so it can be used.
The property dependencies get added to package.json:

{
  "name": "npm-intro",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "jquery": "^3.6.0"
  }
}

Question 6

How do you add express to your package dependencies?

Answer 6

npm install express

Question 7

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

Answer 7

listen( )

Question 8

How do you mount a middleware with an Express application?

Answer 8

Using the use/get method.

Examples:

app.use(function (req, res, next) {
res.send(‘Hello World’)
} )

app.use(function (req, res, next) {
console.log(‘Time: %d’, Date.now( ))
next( )
} )

It happens when I request is received in the server.
Event listener for requests.

Question 9

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

Answer 9

req and res.

request and response.

req is a data-model for the request message:
GET / HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: 192.168.1.40:1337
User-Agent: HTTPie/1.0.3

Question 10

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

Answer 10

application/json

Question 11

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

Answer 11

express.json( ) is a method inbuilt in express to recognize the incoming Request Object as a JSON Object. This method is called as a middleware in your application using the code: app.use(express.json( ));

If the request includes JSON, use it.

Question 12

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

Answer 12

It defines what is to be done with the data.

The method name is just for semantics.

Question 13

What is Webpack?

Answer 13

It’s a tool that lets you bundle your JavaScript applications (supporting both ESM and CommonJS), and it can be extended to support many different assets such as images, fonts and stylesheets.

Bundles modules.

Question 14

How do you add a devDependency to a package?

Answer 14

npm install –save-dev webpack

or

npm i -D webpack

Question 15

What is an NPM script?

Answer 15

An npm script is a convenient way to bundle common shell commands for your project.

Command line shortcuts.

Question 16

How do you execute Webpack with npm run?

Answer 16

Add a script in package.json

Ex:

“scripts”: {
“build”: “webpack”,
“test”: “echo "Error: no test specified" && exit 1”
},

Question 17

What kind of modules can Webpack support?

Answer 17

ECMAScript modules. CommonJS modules. AMD modules.

Question 18

What does express.static( ) return?

Answer 18

It returns a middleware function. Programmed to look in directory and sort.

Question 19

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

Answer 19

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

__dirname is an absolute path.

Question 20

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

Answer 20

The path.join( ) method joins all given path segments together using the platform-specific separator as a delimiter( / ), then normalizes the resulting path.