I'm using DevExtreme and knockout. I want to fetch JSON-Data from a server and save it into an observable.

Current approach:

var dataArray = ko.observableArray();
var dataId = ko.observable("");

MyApp.overview = function (params) {
    "use strict"; 

    var viewModel = {
        [...]
    }

    return viewModel;
};

function getDataFromJson() {
    $.ajax({
        url: 'http://localhost:56253/test/3?format=json',
        dataType: 'json',
        success: function (data) {
            var entries = $.map(data, function (item) { return new entry(item) });
            // first entry is ID
            for (var i = 1; i < entries.length; i++) {
                dataArray.push(entries[i]);
            }
        }
    });
}

function getIDFromJson() {
    $.ajax({
        url: 'http://localhost:56253/test/3?format=json',
        dataType: 'json',
        success: function (data) {
            dataId(data.ID);
        }
    });
}

function entry(data) {
    this.A = data.A,
    this.B = data.B,
    this.C = data.C
}

I'm new to these scenarios, so I'm not sure if my apporach. For testing, I'm calling the functions to get the JSON-Data manually via buttons, and I get the needed data, but the observables both contain this:

function c(){if(0<arguments.length)return c.tb(c[E],arguments[0])&&(c.ga(),c[E]=arguments[0],c.fa()),this;a.l.oc(c);return c[E]}

What am I missing? Or is this approach bad practice in general?