NPM/Express/Babel

Question 1

What is NPM?

Answer 1

Node package manager, software registry that makes it easy for JS developers to share reusable code to solve problems
- website, command line client, registry

Question 2

What is a package?

Answer 2

directory with one or more files inside and package.json file

Question 3

How can you create a package.json with npm?

Answer 3

npm init -y (for default) in current directory

Question 4

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

Answer 4

Any other packages that your package depends on

**npm install package-name

Question 5

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

Answer 5

• the package name is added under “dependencies” in package.json
• npm will downloads listed dependencies under node-modules directory

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

app.listen

Question 8

How do you mount a middleware with an Express application?

Answer 8

app.use()

Question 9

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

Answer 9

request and response objects

Question 10

What is the purpose of the Content-Type header in HTTP request and response messages?

Answer 10

In a response, the header tells the client what kind of file type the returned content is
In a request, the client tells the server what kind of information is being sent

Question 11

What does express.static() return?

Answer 11

a middleware function that returns static files such as images, CSS files, and JavaScript files in the specified root directory

Question 12

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

Answer 12

full directory name of current module or absolute path

Question 13

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

Answer 13

concatenates individual segments or strings together to form a file path

Question 14

middleware functions (express)

Answer 14

functions that have access to the request object (req), the response object (res), and the next middleware function in the application’s request-response cycle

Question 15

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

Answer 15

application/json

Question 16

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

Answer 16

It parses incoming requests from JSON

Returns middleware that only parses JSON and only looks at requests where the Content-Type header matches the type option.

only need this that is supposed to receive json

Question 17

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

Answer 17

Tells the server what the client is trying to do (ex. get information, post information, delete information, etc)

Question 18

What is Webpack?

Answer 18

a tool that allows let us take JS modules and bundle them together

**module butler

Question 19

How do you add a devDependency to a package?

Answer 19

npm install –save-dev webpack

npm install –save-dev

Question 20

What is an NPM script?

Answer 20

Written in package.json as key/value pair, a script to help to automate tasks (command line command) name: key, value: what you want to execute

Question 21

How do you execute Webpack with npm run?

Answer 21

List it as a script under package.json “scripts”

Question 22

How are ES Modules different from CommonJS modules?

Answer 22

No export.modules or require

**export keyword in front of whatever you want to export, then import _ from “file path”

Question 23

What kind of modules can Webpack support?

Answer 23

ES2015 import, CommonJS require, AMD define/require, @import statment css/sass/less, img url in stylesheet url() or HTML img src file

Question 24

What is Babel?

Answer 24

JavaScript compiler/toolchain used to convert JS code to older versions to be compatible with older browsers and environments

Question 25

What is a Plug-in?

Answer 25

a software component that adds a specific feature to an existing computer program.

Question 26

What is a Webpack loader?

Answer 26

transformations that are applied to the source code of a module. They allow you to pre-process files as you import or “load” them

Question 27

How can you make Babel and Webpack work together?

Answer 27

in your webpack config object:

• loader: babel-loader
• Options property -> plugins: [] array of wanted plugins