How does CORS work with the Fetch API in JavaScript?

Can you explain how CORS works with the Fetch API in JavaScript?

CORS, or Cross-Origin Resource Sharing, is a security feature that allows or restricts resources requested from another domain. When using the Fetch API, if you try to fetch a resource from a different origin, the server must include specific headers to allow the request.

What headers does the server need to include for CORS?

The server should include the Access-Control-Allow-Origin header, which specifies which origins are permitted to access the resource. It can also include headers like Access-Control-Allow-Methods and Access-Control-Allow-Headers to specify allowed methods and headers.

What happens if the CORS headers are not set?

If the CORS headers are not set, the browser will block the request, and you'll see a CORS error in the console. This is to protect users from potentially harmful cross-origin requests.

Can I bypass CORS restrictions during development?

Yes, during development, you can use tools like browser extensions or set up a local proxy server to bypass CORS restrictions. However, this should not be done in production.