Stop 05 · Backend with Node.js & ExpressTopics · 6/8

Request Validation

Part of the Full Stack Developer Roadmap

In short

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.

More topics at this stop

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

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