DevExtreme dxRadioGroup

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/knockout/3.1.0/knockout-min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/globalize/0.1.1/globalize.min.js"></script>
<script src="http://cdn3.devexpress.com/jslib/14.2.3/js/dx.phonejs.js"></script>
<link rel="stylesheet" href="http://cdn3.devexpress.com/jslib/14.2.3/css/dx.common.css">
<link rel="stylesheet" href="http://cdn3.devexpress.com/jslib/14.2.3/css/dx.ios.default.css">
<div data-bind="dxRadioGroup: { dataSource: items, layout: 'horizontal', value: defaultvalue, valueExpr: 'value' }"></div>

JavaScript

var items = [
        { text: "Tea", value=1 },
        { text: "Coffee", value=2 },
        { text: "juice", value=3 }
    ];
    
var viewModel = {
    items: items,
    defaultvalue: 1)
};
    
ko.applyBindings(viewModel);