What is encoding and decoding buffers?

0-2 years experience

1. 1You need to read a UTF‑8 string from a file and send it over a WebSocket as a Buffer. How would you encode the string into a Buffer and then decode it back on the client?
2. 2If you call Buffer.from('hello') without specifying an encoding, what encoding does Node assume, and what would happen if the source string is actually UTF‑16?
3. 3Write a short snippet that takes a Buffer containing JSON data and converts it to a JavaScript object.

2-5 years experience

1. 1Your service receives binary payloads from a legacy system that uses ISO‑8859‑1 encoding, but your Node.js code assumes UTF‑8. The data appears garbled. How would you diagnose and fix the encoding issue?
2. 2While processing a large file stream you notice memory usage spikes when you concatenate Buffers with Buffer.concat. What alternatives could you use to keep memory usage low?
3. 3Explain why using Buffer.toString('base64') for transmitting binary data over HTTP might be preferable to raw binary, and what trade‑offs it introduces.

5-8 years experience

1. 1Design a Node.js microservice that ingests high‑throughput video frames as Buffers, decodes them to raw pixel data, and forwards them to a processing pipeline. What considerations around buffer allocation, back‑pressure, and zero‑copy would you address?
2. 2Your team needs to support both UTF‑8 and UTF‑16 payloads in a single API endpoint. How would you structure the request handling to safely detect and decode the incoming Buffer without introducing security risks?
3. 3A recent performance regression was traced to repeated Buffer.allocUnsafe calls that left sensitive data exposed. How would you audit and remediate this across the codebase?

8+ years experience

1. 1We are migrating a legacy system that stores records as binary blobs with a custom encoding to a new JSON‑based API. How would you plan the transition to ensure backward compatibility while minimizing impact on downstream services?
2. 2Across multiple services we have inconsistent conventions for Buffer encoding (some use 'utf8', others 'latin1'). As a staff engineer, how would you drive a unified strategy and enforce it in CI/CD pipelines?
3. 3Consider a scenario where a shared library provides a Buffer‑based protocol that must evolve without breaking existing clients. What versioning and compatibility mechanisms would you introduce at the architecture level?