JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://github.com/downloads/SteveSanderson/knockout/knockout-2.0.0.js"></script>
<div id='theDiv'>
    <span data-bind="text: name"></span> 
    <div data-bind="if: badthing">+<span data-bind="text: priceFormatted"></span></div>
</div>

JavaScript

var vm = {
    name: ko.observable("The name"),
    badthing: ko.observable(false),
    priceFormatted: ko.observable('Eleventy bajillion dollars')
};

ko.applyBindings(vm, document.getElementById('theDiv'));