What is a WebSocket object?

0-2 years experience

1. 1How would you create a WebSocket connection from a Node.js client to a server, and which events would you listen for?
2. 2If the server closes the WebSocket unexpectedly, what steps does the WebSocket object take, and how would you handle it in code?
3. 3What’s the practical difference between using the browser’s native WebSocket class and the ws library’s WebSocket object in Node.js?

2-5 years experience

1. 1We need to add a real‑time chat feature using WebSockets. Walk me through how you’d manage the WebSocket object lifecycle on the server and what reconnection trade‑offs you’d consider.
2. 2During load testing, some messages are dropped after the WebSocket emits a 'close' event. How would you debug this, and what could cause the WebSocket object to close prematurely?
3. 3Why might you choose to send JSON strings over a WebSocket object instead of raw binary, and how would you handle parsing errors on the receiving side?

5-8 years experience

1. 1Our service must support 100k concurrent WebSocket connections. How would you design the WebSocket object handling layer to scale, considering memory usage, back‑pressure, and graceful shutdown?
2. 2We’re migrating from a custom TCP socket implementation to the Node.js WebSocket object. What edge cases and compatibility concerns would you watch for during the migration?
3. 3Describe how you’d implement per‑connection rate limiting using the WebSocket object without affecting other connections.

8+ years experience

1. 1Our platform spans multiple data centers behind a TLS‑terminating load balancer. How would you architect WebSocket object usage across services to ensure session affinity, failover, and observability?
2. 2We need to evolve our real‑time API while keeping backward compatibility for clients using older WebSocket message formats. How would you structure versioning and deprecation at the WebSocket object layer?
3. 3Discuss the trade‑offs of moving WebSocket handling into a dedicated microservice versus embedding it in each application server, focusing on operational overhead and scaling.