nodejs-expert

Centralized error handling in Express uses middleware wrappers around route handlers to catch errors consistently and pass them to a global error handler. This approach unifies error responses, enables typed error hierarchies, and ensures async errors don't crash the server.

NestJS backend structure uses modular architectures with service layers, repository patterns, and clear separation between controllers, services, and data access. This structure enables testability, reusability, and scales across team size and API complexity.

DTO validation in Node.js backends applies schemas to incoming request payloads before processing, catching malformed or malicious input early. Combined with type safety, it prevents injection attacks and ensures downstream code receives only valid data.

While both Prisma and TypeORM handle database access, using one consistently within your backend prevents abstraction conflicts and simplifies repository patterns. Choose based on your schema design preference and async query patterns.

Async patterns in Fastify include proper error wrapping, avoiding shared mutable state in handlers, and sequencing database operations through service layers. These prevent race conditions and ensure request isolation in high-concurrency scenarios.

GraphQL and REST both benefit from unified error hierarchies and centralized handling, but GraphQL requires errors within the response payload rather than HTTP status codes. Both patterns work with Express, NestJS, and Fastify frameworks.