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List elementary stream types. | Streams | nodejs Interview Questions | NextRound.in

Questions

3 of 24

1What are streams?

2What are advantages of streams.

3List elementary stream types.

4write code of a stream to read a local file in node js

5What is the purpose of the `stream.pipeline()` function in Node.js?

6Explain the difference between `pipe()` and `on('data')` when working with streams.

7What is the purpose of the `unpipe()` method in Node.js streams, and how does it work?

8How can you handle memory usage when dealing with large files in Node.js streams?

9What is the pause() method used for in a readable stream, and how can you resume data flow?

10How do you handle stream errors when working with async/await in Node.js?

11What is the purpose of the `stream.finished()` utility in Node.js?

12What is the purpose of the `highWaterMark` option when creating a readable stream?

13Explain the difference between `ObjectMode` and `Buffer` mode in a readable stream.

14How can you handle cleanup operations when working with streams?

15Explain the difference between a flowing and a non-flowing readable stream.

16Explain the concept of object streams and provide an example use case.

17How can you handle errors in Node.js streams?

18What is the `end` event in a readable stream, and how is it different from the `finish` event in a writable stream?

19How can you create a custom Transform stream in Node.js?

20Explain the concept of piping in Node.js streams.

21What is backpressure in Node.js streams, and how can you handle it?

22What is the difference between the `data` event and the `readable` event in a readable stream?

23Create a readable stream

24What is the purpose of pipeThrough function

nodejs

File Operations

Performance Optimisation

03 / 24

List elementary stream types.

Difficulty: 4/10

Node.js streams, stream types, I/O handling

There are four fundamental stream types within Node.js:

1
Writable: streams to which data can be written (for example, fs.createWriteStream()).
2
Readable: streams from which data can be read (for example, fs.createReadStream()).
3
Duplex: streams that are both Readable and Writable (for example, net.Socket).
4
Transform Duplex streams that can modify or transform the data as it is written and read (for example, zlib.createDeflate()).

Scenario Questions

0-2 years experience

1How would you copy a file using Node.js streams? Which stream types would you create and how would you connect them?
2If you build a Transform stream but only implement the _write method, what behavior would you observe at runtime?
3What happens when you pipe a Readable directly into a Writable without handling backpressure, and how can you mitigate it?

Follow-up Questions

Which stream type would you pick for a simple data filter and why?
How does backpressure differ between Readable and Transform streams?
What testing strategy would you use for a custom stream implementation?

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2-5 years experience

1We need to read line‑delimited JSON from a socket, transform each object, and write it to another service. Which combination of stream types would you choose and how would you handle errors?
2A pipeline that uses a Duplex stream started hanging after a recent change. Walk me through how you'd debug the issue and which aspects of Duplex streams you’d inspect.
3Why might a Transform stream be preferable to a plain Writable when you need to modify data on the fly before persisting it?

5-8 years experience

1Design a high‑throughput log processing system that reads from multiple sources, filters, and writes to storage. Explain how you’d compose Readable, Transform, and Writable streams to maintain backpressure and scalability.
2We must support both object mode and binary mode in a streaming API. Discuss the trade‑offs of using a Duplex versus a Transform stream for this requirement.
3If you need to add gzip compression to an existing pipeline without breaking current consumers, how would you integrate a Transform stream and what edge cases would you watch for?

8+ years experience

1Our platform is moving from callback‑based file I/O to a unified streaming architecture across services. What architectural considerations guide whether you expose raw stream types versus higher‑level pipeline abstractions to downstream teams?
2When migrating a legacy monolith that uses custom event emitters for data flow to Node.js streams, how would you plan the transition to minimize disruption and ensure compatibility?
3At scale, how would you monitor and manage backpressure across distributed Node.js services that communicate via streams, and what organization‑wide patterns would you enforce?