String.prototype.format = function() {
  return String.format(this, arguments.length == 1 ? arguments[0] : arguments);
};

String.format = function(source, params) {
  var _toString = function(obj, format) {
    var ctor = function(o) {
      if (typeof o == 'number')
        return Number;
      else if (typeof o == 'boolean')
        return Boolean;
      else if (typeof o == 'string')
        return String;
      else
        return o.constructor;
    }(obj);
    var proto = ctor.prototype;
    var formatter = typeof obj != 'string' ? proto ? proto.format || proto.toString : obj.format || obj.toString : obj.toString;
    if (formatter)
      if (typeof format == 'undefined' || format == "") 
        return formatter.call(obj);
      else
        return formatter.call(obj,format);
    else
      return "";
  };
  if ( arguments.length == 1 )
    return function() {
      return String.format.apply( null, [source].concat( Array.prototype.slice.call( arguments, 0 ) ) );
    };
  if ( arguments.length == 2 && typeof params != 'object' && typeof params != 'array')
    params = [ params ];
  if ( arguments.length > 2 ) 
    params = Array.prototype.slice.call(arguments, 1);
  source = source.replace(/\{\{|\}\}|\{([^}: ]+?)(?::([^}]*?))?\}/g, function(match, num, format) {
    if (match == "{{") return "{";
    if (match == "}}") return "}";
    if (typeof params[num] != 'undefined' && params[num] !== null) {
      return _toString(params[num], format);
    } else {
      return "";
    }
  });
  return source;
};