CORS header error

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://**. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).

if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {    if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']) && $_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD'] == 'POST') {
        header('Access-Control-Allow-Origin: *');
        header('Access-Control-Allow-Headers: X-Requested-With, content-type, access-control-allow-origin, access-control-allow-methods, access-control-allow-headers');
    }
    exit;
}header('Content-type: application/json');
header('Access-Control-Allow-Origin: *');