Allowing Access to API from another Domain, without knowing the Domain to Add.

php

// Allow from any origin
    if (isset($_SERVER['HTTP_ORIGIN'])) {
        //header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
        header("Access-Control-Allow-Origin: *");
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Max-Age: 86400');    // cache for 1 day
    } else {
        header("Access-Control-Allow-Origin: *");
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Max-Age: 86400');    // cache for 1 day
    }
    // Access-Control headers are received during OPTIONS requests
    if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
            header("Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS");         

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
            header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");
            //header("Access-Control-Allow-Headers: X-Requested-With");

    }
    if("OPTIONS" == $_SERVER['REQUEST_METHOD']) { exit(0); }