Reason: CORS header 'Access-Control-Allow-Origin' missing ajax code example

Example: cors header ‘access-control-allow-origin’ missing IN PARTICULAR CAKEPHP API

header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST, GET, PUT, PATCH, DELETE, OPTIONS');
header('Access-Control-Allow-Headers: *');
if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {
    exit(0);
}