JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://knockoutjs.com/downloads/knockout-3.2.0.js"></script>
The name is <span data-bind="text: personName"></span>
<button type="button" data-bind="click: changeName">Click Me!</button>

JavaScript

var myViewModel = {
    personName: ko.observable('Foo'),
    personAge: ko.observable(123)
};

myViewModel.changeName = function() {
    var newName = myViewModel.personName() === 'Foo' ? 'Bar' : 'Foo';
	myViewModel.personName(newName);
}
ko.applyBindings(myViewModel);