Knockoutjs.com - Control types example

http://knockoutjs.com/examples/controlTypes.html

HTML

<script src="http://github.com/downloads/SteveSanderson/knockout/knockout-2.1.0.js"></script>
<div class='liveExample'>    
        <h3>Radio View model</h3>
        <table>
        <tr>
            <td class="label">Radio buttons:</td>
            <td>
                <label><input name="Test" type="radio" value="A" data-bind="checked: radioSelectedOptionValue" />Alpha</label>
                <label><input name="Test" type="radio" value="B" data-bind="checked: radioSelectedOptionValue" />Beta</label>
            </td>
        </tr>
    </table>  
    A-<span data-bind="text: A"></span>
    B-<span data-bind="text: B"></span>
</div>

JavaScript

var viewModel = function() {
    this.radioSelectedOptionValue = ko.observable();
    this.A = ko.computed(
        {
            read: function() {
                return this.radioSelectedOptionValue() == "A";
            },
            write: function(value){
                if (value)
                    this.radioSelectedOptionValue("A");
            }
        }
    ,this);
    this.B = ko.computed(
        {
            read: function() {
                return this.radioSelectedOptionValue() == "B";
            },
            write: function(value){
                if (value)
                    this.radioSelectedOptionValue("B");
            }
        }
    ,this);        
};
ko.applyBindings(new viewModel());