Decorators: Example Decorator

emailReportCardToParent.js

var EmailReportCardToParent = function(obj) {
  this.obj = obj
  this.decorate()
  return obj
};

EmailReportCardToParent.prototype = _.extend(EmailReportCardToParent.prototype, {

  // specify the method that you want to decorate
  methodToDecorate: 'saveReportCardAsPDF',

  decorate: function() {
    var self = this

    // store the original function for use in a closure
    var originalFn = this.obj[this.methodToDecorate]
    
    // define the decorated function, which captures the originalFn in its closure
    var decoratedFn = function(html) {
      // call the decorator method with the result of the originalFn as the argument
      var res = originalFn(html)
      self.sendPdfAsEmail(res)
      return res;
    };
    
    // override the method on the object with the new decoratedFn
    this.obj[this.methodToDecorate] = decoratedFn
  },

  sendPdfAsEmail: function() {
    // some actions here to
    // send email to parent
  }

});

// Example usage
new EmailReportCardToParent(new GenerateReportCard())).run()

I think you have a couple too many closing parenthesis on the last line.