CORS (Cross-Origin Resource Sharing)

Browsers block cross-origin requests by default. The server must explicitly allow them via headers.

Overview

Browsers block cross-origin requests by default. The server must explicitly allow them via headers.

Code Example

res.setHeader("Access-Control-Allow-Origin", "http://localhost:5173");

Web Development Context

In modern web development, understanding CORS (Cross-Origin Resource Sharing) is crucial. Node.js is widely used for building APIs, real-time applications, and microservices. Mastery of this concept allows you to build efficient, scalable, and secure backend systems.

Common Mistakes

• Blocking the event loop with heavy synchronous tasks.
• Exposing secrets in code instead of environment variables.
• Forgetting to handle promise rejections.

Next Steps

To solidify your understanding, review the related references and try out the practice challenges.