JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cloud.github.com/downloads/SteveSanderson/knockout/knockout-2.0.0.js"></script>
<script src="https://raw.github.com/SteveSanderson/knockout.mapping/master/build/output/knockout.mapping-latest.js"></script>
Current Value:<span data-bind="text:saved_value"></span><br/>
<input data-bind="event:{change:value_changed},value:saved_value"></input>

JavaScript

var data = {
    saved_value:"1",
    value_changed: function(data){
        alert(data.saved_value());
    }
};
var viewModel = ko.mapping.fromJS(data);
ko.applyBindings(viewModel);