Error: Access to fetch at 'localhost/userProject/userRegistration.php' from origin 'localhost:19006' has been blocked by CORS policy?

Question

CORS

I studied the issue, installed the Express and cors libraries but did not help

Answer 1

localhost and localhost:19006 are different sites from the browser's point of view.
CORS headers must be returned, including for OPTIONS requests.

header('Access-Control-Allow-Origin: ' . $_SERVER['HTTP_ORIGIN']);
header('Access-Control-Allow-Credentials: true');
header('Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept');
header('Access-Control-Allow-Methods: GET, POST, OPTIONS');
header('Vary: Origin');

And if you use cookies, then you also need to set withCredentials=truefor AJAX requests.