HTTP / Express.js

Question 1

What is a client?

Answer 1

A device that requests services from a server.

Question 2

What is a server?

Answer 2

A device that provides services to clients.

Question 3

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

Answer 3

The GET method.

Question 4

What three things are on the start-line of an HTTP request message?

Answer 4

HTTP method, the request target, and the HTTP version.

Question 5

What three things are on the start-line of an HTTP response message?

Answer 5

HTTP version, status code, and status text.

Question 6

What are HTTP headers?

Answer 6

Key value pairs that allow the client and server to pass additional information in an HTTP request or response.

Question 7

Where would you go if you wanted to learn more about a specific HTTP Header?

Answer 7

MDN

Question 8

Is a body required for a valid HTTP request or response message?

Answer 8

No.

Question 9

How do you add express to your package dependencies?

Answer 9

npm install express

Question 10

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

Answer 10

express.listen(portNumber, callBack);

Question 11

How do you mount a middleware with an Express application?

Answer 11

express.use((req, res, next) => {
code block here
})

Question 12

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

Answer 12

req, res, and next

Question 13

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

Answer 13

application/json

Question 14

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

Answer 14

The middleware function parses posted JSON strings from requests and adds them as the req.body object. You would need it whenever the server deals with JSON input.

Question 15

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

Answer 15

The significance is for humans, servers can technically be programmed to respond in any way possible to HTTP request methods.

Question 16

What does express.static() return?

Answer 16

The serveStatic middleware function.

Question 17

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

Answer 17

A string that lists the absolute file path of the module the directory is in.

Question 18

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

Answer 18

Joins the arguments into a path.

Question 19

What does fetch() return?

Answer 19

A promise for a response object.

Question 20

What is the default request method used by fetch()?

Answer 20

GET

Question 21

How do you specify the request method (GET, POST, etc.) when calling fetch?

Answer 21

Specify method in the init object argument: fetch(url, { method: ‘METHOD’ })