express.js

Question 1

How do you add express to your package dependencies?

Answer 1

npm install express –save

Question 2

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

Answer 2

app.listen([port[, host[, backlog]]][, callback])

Question 3

How do you mount a middleware with an Express application?

Answer 3

app.use([path,] callback [, callback…])

Question 4

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

Answer 4

request and response object

Question 5

What is a middleware function?

Answer 5

Middleware functions are 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 6

What tasks can a middleware function perform?

Answer 6

-Execute any code.
-Make changes to the request and the response objects.
-End the request-response cycle.
-Call the next middleware function in the stack.

Question 7

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

Answer 7

application/json

Question 8

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

Answer 8

It parses incoming JSON requests and puts the parsed data in req.body.

Need it when we want to accept JSON.

Question 9

What does express.static() return?

Answer 9

serveStatic function

Question 10

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

Answer 10

absolute path to the current module

Question 11

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

Answer 11

combines multiple strings into a directory path format