JSFiddle - React, Tailwind, and code Playground

HTML

<script src="code.jquery.com/jquery-1.7.2.js"></script>
<script src="knockoutjs.com/js/knockout-2.1.0.js"></script>
<script src="documentcloud.github.com/underscore/underscore.js"></script>
<script src="//code.jquery.com/jquery-1.7.2.js"></script>
<script src="//knockoutjs.com/js/knockout-2.1.0.js"></script>
<script src="//documentcloud.github.com/underscore/underscore.js"></script>
<script>
// from http://knockoutjs.com/documentation/template-binding.html
/* ---- Begin integration of Underscore template engine with Knockout. Could go in a separate file of course. ---- */
ko.underscoreTemplateEngine = function () { }
ko.underscoreTemplateEngine.prototype = ko.utils.extend(new ko.templateEngine(), {
    renderTemplateSource: function (templateSource, bindingContext, options) {
        // Precompile and cache the templates for efficiency
        var precompiled = templateSource['data']('precompiled');
        if (!precompiled) {
            precompiled = _.template("<% with($data) { %> " + templateSource.text() + " <% } %>");
            templateSource['data']('precompiled', precompiled);
        }
        // Run the template and parse its output into an array of DOM elements
        var renderedMarkup = precompiled(bindingContext).replace(/\s+/g, " ");
        return ko.utils.parseHtmlFragment(renderedMarkup);
    },
    createJavaScriptEvaluatorBlock: function(script) {
        return "<%= " + script + " %>";
    }
});
ko.setTemplateEngine(new ko.underscoreTemplateEngine());
/* ---- End integration of Underscore template engine with Knockout ---- */

</script>


<div data-bind="template: 'test-template'"></div>

<script type="text/html" id="test-template">
    <p>template rendered</p>

    <% if (testval()) { %>
        <p>testval true</p>
    <% } %>

</script>
<script>

var vm = {
    testval: ko.observable(false)
};

setTimeout(function(){
    vm.testval(true);
}, 1000);


ko.applyBindings(vm);

</script>