valore undefined in call back promise

[techno]

Ciao a tutti
Ho questo script:

function result(){
let myPromise = new Promise(function(resolve, rejiect) {
            resolve(xajax(formdata, "/script/playlist.php"));
        });


        myPromise.then(
            function(value) {
                alert(value);


            },
            function(error) {
                alert(error);
            },


        );
}


function xajax(formdata, url) {
    $.ajax({
        url: url,
        data: formdata,
        method: "POST",
        contentType: false,
        processData: false,
        success: function(response) {
            return response;
        },
        error: function(response) {
            return response;
        }
    });
}

perche in alert mi da sempre undefined?