Set your Publisher ID in src/config/ads.ts to display live ads.
CORS (Cross-Origin Resource Sharing) Demystified
Same-Origin Policy, Preflight OPTIONS requests, and server headers
CORS is a browser security mechanism that restricts scripts on one origin from accessing resources on a different origin unless the server explicitly grants permission via HTTP headers.
Understanding Same-Origin vs Cross-Origin
Origin definition: Protocol (https) + Domain (api.codexia.org) + Port (443). If any of the three differ, it is Cross-Origin.
Same-Origin Policy (SOP): Browsers block client-side scripts from reading responses from other origins by default.
Server Headers: The destination server must respond with Access-Control-Allow-Origin: * (or specific domain).
Preflight Requests: For non-simple requests (like POST with JSON), browsers automatically send a preliminary OPTIONS request before sending the actual payload.
CORS is enforced strictly by the client browser, NOT the server. A curl command or Node.js script will never experience CORS errors.
Set your Publisher ID in src/config/ads.ts to display live ads.
Test Yourself With Exercise
Where is CORS (Cross-Origin Resource Sharing) enforced?