Minimal String Template Source for Knockout

example.js

var templateEngine = createNativeStringTemplateEngine();

      templateEngine.addTemplate('gigaScroll', "\
        <div id=\"viewport\">\
          <div id=\"gigaDiv\" data-bind=\"style: { height: gigaDivHeight() + 'px' }\">\
            <ul data-bind=\"foreach: visibleItems, style: { paddingTop: offsetTop() + 'px' }\">\
              <li data-bind="text: name" />
            </ul>\
          </div>\
        </div>");

      ko.renderTemplate("gigaScroll", viewModel, { templateEngine: templateEngine }, element, "replaceNode" );

src.js

// Less verbose implementation of 
// http://www.knockmeout.net/2011/10/ko-13-preview-part-3-template-sources.html


  var StringTemplate = function(text) {
    var _data = {};
    var _text = text;
    this.data = function(key, value) {
        if (!value) return _data[key];
        _data[key] = value;
    }
    this.text = function(newValue) {
        if (!newValue) return _text;
        _text = newValue;
    }
  }


  function createNativeStringTemplateEngine() {
    var _templates = {};
    var _nativeEngine = new ko.nativeTemplateEngine();

    _nativeEngine.makeTemplateSource = function(templateName) {
        return _templates[templateName];
    }

    _nativeEngine.addTemplate = function(name, body) {
        _templates[name] = new StringTemplate(body);
    }

    return _nativeEngine;
  }

Cool! A couple of issues:

1. Checking the falsy-ness of value and newValue is not the same as checking arguments.length - knockout won't be able to set null or empty string. probably not and issue for text but likely for data.
2. you will have a better memory footprint per template to put data and text on StringTemplate.prototype rather than in the closure. (You are newing it up like a class for a reason, right?)