knockoutjs & underscore template

chatroom.js

 /* ---- 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 ---- */