A small template rendering engine in JS ... uses Function constructor, unfortunately

000-lessthan140chars.js

function(b,c){return b.replace(/{[\w\.\(\)]+}/g,function(a){a=a.replace(/[\{\}]/g,"");try{with(c)return eval(a)}catch(b){return""}})};

Example using twitters API

goto http://jsfiddle.net/netroy/HA8es/ for a running example using this renderer

NewTemplater.js

// Similar to the older version, without eval & with (sort-of)

function render(template, data) {
  return template.replace(/\{[\w\.\-\(\)]+\}/g, function(match){
    var token = match.replace(/[\{\}]/g,"");
    try {
      return (new Function("data", "return data." + token))(data);
    } catch(e) {
      return "";
    }
  });
}

OldTemplater.js

// templates support object & function ... like "{abcd}" or "xyz.pqr" or "GL.package.class.init(arguments.toString())"
// data is an object with values that would be used for rendering .... like {abcd:"something",xyz:{pqr:123},arguments:[]}

function render(template, data){
  return template.replace(/{[\w\.\-\(\)]+}/g, function(match){
    var token = match.replace(/[\{\}]/g,"");
    try {
      with(data) {
        return eval(token);
      }
    } catch(e) {
      return "";
    }
  });
}

As of ES5, eval executes in a private scope, so its okay to use it if needed.
More important thing to remove is the with statement, but without that, i haven't figured out how to have function calls in templates.
for just namespaced objects, with can be replaced by a eval("data."+token)

Will have to dig more into this. I got the above snippet from Crockford