var loginCred = new Object();
loginCred.Username = $('#userName').val();
loginCred.Password = $('#password').val();
loginCred.RememberMe = $('#rememberMe').checked;

var myJsonObject = JSON.stringify(loginCred);

$.ajaxSetup({ cache: false });
$.ajax({
    type: "POST",
    contentType: "application/json; charset=utf-8",
    url: "/Account/LogOnAjax/",
    data: myJsonObject,
    dataType: "json",
    success: function(data) {
        PostCredentialsSuccess(data);
    }

});

var myJsonObject = JSON.stringify(loginCred);

data: loginCred,

data: myJsonObject,

data:{"jsondata":myJsonObject}