Express JS

Question 1

How do you add express to your package dependencies?

Answer 1

npm install express

Question 2

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

Answer 2

app.listen(port, callback)

Question 3

How do you mount a middleware with an Express application?

Answer 3

Using the app.use(callback) method

Question 4

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

Answer 4

req(request) and res(response)

Question 5

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

Answer 5

application/json

Question 6

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

Answer 6

It parses implicit key-value pairs in an HTTP request into a JSON, and assigns it to req.body; it is necessary when the client sends a JSON

Question 7

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

Answer 7

It is used semantically for deciding the proper middleware function to use

Question 8

What does express.static() return?

Answer 8

A middleware function that adds a specified directory from which to serve files

Question 9

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

Answer 9

It is a string of the absolute path to the directory containing the module

Question 10

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

Answer 10

It takes strings of paths, and returns a composite of the paths