Node.js Streams & Buffers 2

Question 1

Which stream base class should you extend to implement a custom stream that both reads input and produces transformed output?

Accepted Answer

stream.Transform

Answer

stream.Transform is a Duplex subclass where the output is computed from the input, making it ideal for data conversion tasks like compression or encryption.

Question 2

What is the purpose of the highWaterMark option when creating a Node.js stream?

Accepted Answer

Defines the internal buffer size threshold before backpressure is applied

Answer

highWaterMark specifies the number of bytes (or objects in object mode) that can accumulate in the internal buffer before backpressure is triggered.

Question 3

Which internal method must you implement when subclassing stream.Readable to provide data to consumers?

Accepted Answer

_read()

Answer

The _read() method is called by the stream internals when a consumer requests more data; you call this.push() inside it to supply chunks.

Question 4

Why is stream.pipeline() preferred over readable.pipe() for production code?

Accepted Answer

It handles errors and automatically destroys all streams in the pipeline

Answer

stream.pipeline() propagates errors to a callback and destroys all piped streams on failure, preventing resource leaks that pipe() alone does not handle.

Question 5

How do you create a Buffer from a hexadecimal string in Node.js?

Accepted Answer

Buffer.from('deadbeef', 'hex')

Answer

Buffer.from() accepts an encoding as the second argument; passing 'hex' interprets each pair of characters as a byte value.

Node.js Practice Test

Node.js Practice Test

Node.js Streams & Buffers 2