List elementary stream types.

0-2 years experience

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

2-5 years experience

1. 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?
2. 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.
3. 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

1. 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.
2. 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.
3. 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

1. 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?
2. 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?
3. 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?