Mustache Lambda not rendering output

data:

var data = {
   bold: function () {
     return function (text, render) {
         return "<b>" + render(text) + "</b>";
     }
   }
}
res.writeHeader(200, {
    "Content-Type": "text/html"
});
    var stream = mu.compileAndRender('test.html', data);
    stream.pipe(res);

html

 {{#bold}}I'm Bold.{{/bold}}

My function isnt working as expected in node.js, it just outputs the text unchanged.

You could try using the client-side version, which also works in node.js:

// assuming mustache.js is in current directory
var Mustache = require('./mustache');

var data = {
  bold: function () {
    return function (text, render) {
      return "<b>" + render(text) + "</b>";
    }
  }
};

console.log(Mustache.render('{{#bold}}I\'m bold.{{/bold}}', data));