Request Validation

Part of the Full Stack Developer Roadmap.

Summary

Checking that incoming request data matches your expected shape and constraints before your business logic runs — your backend's first line of defense, regardless of what the frontend already validated.

How to Learn This

1Add validation to a POST endpoint using a library like Zod or express-validator.
2Return clear, field-specific error messages your React form can display.
3Never trust the client — validate on the server even if the frontend also validates.

REST API Design

Error Handling

More topics in Backend with Node.js & Express

Node.js Runtime & Event Loop NPM & Package Management Express Basics & Routing Middleware REST API Design Error Handling Environment Variables

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