Phase 1 · Internet & Backend Basics
TopicsCORS
Part of the Backend Developer Roadmap.
Summary
Cross-Origin Resource Sharing — a browser security mechanism that blocks a frontend on one origin from calling an API on another origin unless the server explicitly allows it.
How to Learn This
- 1Trigger a CORS error deliberately by calling an API from a different origin.
- 2Configure CORS headers on an Express server to allow a specific frontend origin.
- 3Learn the difference between simple requests and preflighted (OPTIONS) requests.
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