JavaScript Node.js Basics 4

Question 1

What is the correct way to create a simple HTTP server in Node.js that responds with 'Hello World'?

Accepted Answer

http.createServer((req, res) => { res.writeHead(200); res.end('Hello World'); }).listen(3000);

Answer

You call `http.createServer()` with a callback that uses `res.writeHead()` and `res.end()` to send the response, then chain `.listen()` to start the server.

Question 2

Which Node.js stream type is used for reading data from a source?

Accepted Answer

Readable

Answer

A Readable stream is used to consume data from a source such as a file, HTTP request body, or stdin.

Question 3

What does the `pipe()` method do when used on a Node.js Readable stream?

Accepted Answer

It connects the Readable stream output directly to a Writable stream input

Answer

`readable.pipe(writable)` automatically forwards data chunks from the readable to the writable and handles backpressure.

Question 4

What is backpressure in the context of Node.js streams?

Accepted Answer

A signal from a Writable stream that it cannot accept more data until it drains

Answer

Backpressure occurs when a Writable stream's internal buffer is full and returns `false` from `write()`, signaling the source to pause sending data.

Question 5

In Node.js, what does `Buffer.from('hello', 'utf8')` return?

Accepted Answer

A Buffer containing the UTF-8 encoded bytes of 'hello'

Answer

`Buffer.from(string, encoding)` allocates a new Buffer containing the string encoded in the specified format (UTF-8 here).

JavaScript Practice Test

JavaScript Practice Test

JavaScript Node.js Basics 4