1st tech round. No defined scope of interview. A lot of jargon based question on git, java. Gave few scenarios for version control problems and wanted git commands to solve that scenario

Practice reading and changing existing code (not just writing from scratch). Refactor small Node/Express modules to be more testable; write unit tests (Jest) and small integration tests. Fix/extend React components for performance, accessibility, and maintainability; add unit tests (React Testing Library). MongoDB/Schema changes — write migration-safe updates and tests for queries (edge cases). Be comfortable explaining trade-offs (why a refactor helps, cost of change, backward compatibility). Prepare common MERN pitfalls: callback/Promise leaks, request-timeouts, memory leaks in Node, N+1 DB queries, unhandled rejections, React re-render causes. (General MERN interview topics and best practices can be reviewed in MERN preparation guides).