Node.js Streams & Buffers

Question 1

What is the default string encoding used when creating a Buffer from a string in Node.js?

Accepted Answer

utf8

Answer

Node.js uses 'utf8' as the default encoding when no encoding argument is provided to Buffer.from().

Question 2

Which Node.js stream type is used exclusively for reading data?

Accepted Answer

Readable

Answer

Readable streams are data sources you can consume — examples include fs.createReadStream() and HTTP request objects.

Question 3

What method connects a Readable stream to a Writable stream so data flows automatically?

Accepted Answer

readable.pipe(writable)

Answer

The pipe() method on a Readable stream automatically forwards chunks to the destination Writable stream and manages backpressure.

Question 4

What is the key difference between Buffer.alloc(size) and Buffer.allocUnsafe(size)?

Accepted Answer

allocUnsafe is faster but may contain old memory data; alloc zero-fills the buffer

Answer

Buffer.alloc() initializes memory to zero for safety, while Buffer.allocUnsafe() skips initialization for speed but may expose old process memory.

Question 5

In Node.js streams, what is 'backpressure'?

Accepted Answer

A flow-control mechanism that slows the producer when the consumer cannot keep up

Answer

Backpressure prevents memory exhaustion by signaling the data producer to pause when the consumer's internal buffer is full.

Node.js Practice Test