Как передать значение из JS в PHP?

var handler = function(result) {
    var ID = result.id;
//    console.log(result);
    $.ajax({
        url: '/index.php',
        method: 'GET',
        data: 'id='+ID,
        async: true
    }).success(function(data){
        var userId = data;
        console.log(userId);
    });
}
var dismissUser = handler;
var subUser = handler;

if(!empty($_GET['id'])):
    $id = htmlspecialchars($_GET['id']);
    $user = CRest::call('user.get', ['ID' => $id]);
    Debug($user['result']);
endif;

if(!empty($_POST)):
    file_put_contents('sjax_post.json', json_encode($_POST));
endif;

var hand = function(result) {
    return result.id;
}

var dismissUser = hand;
var subUser = hand;

$.ajax({
    url: 'ajax.php',
    method: 'POST',
    async: true,
    dataType: 'json',
    data: {dismissID: dismissUser, subID: subUser}
}).success(function(data){
    console.log(data);
});

script.js:16 Uncaught TypeError: Cannot read property 'id' of undefined
    at hand (script.js:16)

<p><button class="btn btn-md btn-danger" onclick="BX24.selectUser(dismissUser);"><i class="fas fa-user-times icon"></i> Увольняющийся сотрудник</button></p>
    <p><button class="btn btn-md btn-warning" onclick="BX24.selectUser(subUser)"><i class="fas fa-user-check icon"></i> Замещающий сотрудник</button></p>
    <p><button id="sendData" class="btn btn-md btn-success">Отправить</button></p>
    <script>
var dismissUser = function(result) {
    return result.id;
}
var subUser = function(result) {
    return result.id;
}
        $('#sendData').click(function(){
            $.ajax({
                url: 'configs/ajax.php',
                type: 'POST',
                dataType: 'JSON',
                data: {
                    dismiss: dismissUser,
                    sub: subUser
                },
                success: function(data) {
                    console.log(data);
                    console.log(data['dismiss']);
                    console.log(data['sub']);
                }
            });
        });
    </script>

script.js:2 Uncaught TypeError: Cannot read property 'id' of undefined
    at dismissUser (script.js:2)
    at o (jquery-1.10.0.min.js:6)
    at gn (jquery-1.10.0.min.js:6)
    at Function.x.param (jquery-1.10.0.min.js:6)
    at Function.ajax (jquery-1.10.0.min.js:6)
    at HTMLButtonElement.<anonymous> (index.php?DOMAIN=bitrix24.src&PROTOCOL=0&LANG=ru&APP_SID=28e72300a6508829f611d7a79e9cea9e:19)
    at HTMLButtonElement.dispatch (jquery-1.10.0.min.js:5)
    at HTMLButtonElement.v.handle (jquery-1.10.0.min.js:5)

{"id":"6","name":"Рюрик Давыдов","sub":true,"sup":false,"position":"","photo":"/upload/resize_cache/main/215/100_100_2/myAvatar2.png"}