Express

Question 1

How do you add express to your package dependencies?

Answer 1

‘Npm install express’ into the terminal while in the package directory

Question 2

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

Answer 2

The listen method, takes the port number and a cb function

Question 3

Is a computer a server?

Answer 3

Well… sort of. It runs the program the provides a service, but the computer itself is not a server.

Question 4

Regarding HTTP status messages, what are the general categories for 100, 200, 300, 400, and 500 response codes?

Answer 4

100s —> informational responses
200s —> successful responses
300s —> redirection messages
400s —> client error responses
500s —> server error responses

Question 5

How do you mount a middleware with an Express application?

Answer 5

When calling the use method, pass in the mount path as a parameter before the cb function

Question 6

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

Answer 6

The request object (req) and the response object (res). They also have access to the next middleware function in the applications lifecycle (typically via next).

Question 7

What is the difference between front end and back end code?

Answer 7

Front End: Downloaded onto the users computer (or phone) and then runs on their device. Makes the website look and function the way it does.

Back End: Lives in a centralized location that we control —> typically in the cloud (AWS). Servers receive requests and deliver responses. Typically responses are either data or file(s

Question 8

The first request a browser makes is for a…

Answer 8

Index.html page
Within the index.html, there are lots of other requests (css, js, images, etc.)

Question 9

Middleware is just a fancy name for a…

Answer 9

Function that does something between two other things — in this case request and response

Question 10

What is a RESTful API?

Answer 10

They use a path to determine the specific resource, and a method to dictate the action on that resource

Question 11

Paths pretty much always start with…

Answer 11

/api —> This helps distinguish the front end and back end routing

Question 12

App.use is a ‘weak’ match — what does that mean?

Answer 12

Any requests that start with that path will fire send —> it’s not very concrete
Hence, we typically run app.use() on all paths —> for example checking an API key or including express.json( )

Question 13

When we’re defining specific routes, we use other methods, like…

Answer 13

App.post, app.get, app.patch, etc.

Question 14

Once we send a response, can we send another response?

Answer 14

Nope —> you can only send one response per request.

Question 15

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

Answer 15

Application/json; charset=Utf-8

Question 16

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

Answer 16

It shows the intent of what the request should do.

Question 17

How do you represent a parameter in the path?

Answer 17

Use ‘:parameter-name’

Question 18

How do you access path parameters inside of its code block?

Answer 18

Use ‘req.params’ to get all parameters with :’parameter-name’ as the key and passed in data as the value

Can also use ‘req.params.’parameter-name’ to get a specific parameter

Question 19

Status code 204 is for…

Answer 19

No content. Cannot send data after sending this status code.

Question 20

The property name in the params object is determined by…

Answer 20

:’parameter-name’ in the path

Question 21

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

Answer 21

It parses incoming requests with JSON data —> it populates the parsed data on the request object if successful (as req.object). Useful when you need to parse data into an object.

Question 22

If you see body:undefined in the console where your server is running, what’s the issue?

Answer 22

You probably forgot to add the jsonMiddleware —> app.use(express.json( ))

Question 23

What creates req.body?

Answer 23

It’s created by the json Middleware, and it assigns any JSON data in the request into an object

Question 24

If you add a colon to the request arguments, what is the result?

Answer 24

score:=72 —> sends a number (72)

Question 25

What is the default status code?

Answer 25

200

Question 26

What status code do we use for post and what method do we typically chain on?

Answer 26

201.json(data-to-send)

Question 27

What does Express.static return?

Answer 27

A middleware function serveStatic —> serves files from the directory (path) passed into express.static

Question 28

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

Answer 28

The directory name of the current module.

Question 29

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

Answer 29

It joins all given path segments together into a beautiful final path that is OS specific (YEET)

Question 30

What loads into the browser first?

Answer 30

The index.html document —> then the browser makes additional requests from there

Question 31

StaticMiddleware is typically one of the first on your server —> why?

Answer 31

Any files that need loaded on the page should come first!