JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cloud.github.com/downloads/SteveSanderson/knockout/knockout-2.1.0.js"></script>
<select data-bind="value: state">
    <option value="true">On</option>
    <option value="false">Off</option>
</select>

JavaScript

var model = {
    state: ko.observable(false)
};

ko.applyBindings(model)