How to: Send an invitation to the creator of an event using Calendar Email Extension

ExecuteOrDelayUntilScriptLoaded(init_setDefaultUser,'sp.js');
var currentUser;
var currentUserLoginName;
var currentUserTitle;
function init_setDefaultUser(){
    //get the current user
    var clientContext = new SP.ClientContext.get_current();
    var oWeb = clientContext.get_web();
    currentUser = oWeb.get_currentUser();
    clientContext.load(currentUser);
    clientContext.executeQueryAsync(onQuerySucceededCurrentUser, onQueryFailedCurrentUser);
}
function onQueryFailedCurrentUser(sender, args) { }
function onQuerySucceededCurrentUser() {
    //get login name and display name of the current user
    currentUserLoginName = currentUser.get_loginName(); 
    currentUserTitle = currentUser.get_title();
    //call fillDefaultUser 
    fillDefaultUser();
}
function fillDefaultUser()
{
    //fill the second people picker
    fillPeoplePickerWithCurrentUser(2);
}
function fillPeoplePickerWithCurrentUser(pickerNo)
{
    if(currentUser != null)
    {
      //get the people picker with the given number
      var pp = getPickerImputElement(pickerNo);
      if(pp != null)
      {
          //build entities xml
          var key = currentUserLoginName;
          var dispval = currentUserTitle;
          var xml = '<Entities Append="False" Error="" Separator=";" MaxHeight="3">';
          xml = xml + '<Entity Key="' + key + '" DisplayText="' + dispval + '" IsResolved="True" Description="' + key + '"><MultipleMatches /></Entity>'
          xml = xml + '</Entities>';
          //call EntityEditorCallback
          EntityEditorCallback(xml, pp.id, true);
      }
    }
}
function getPickerImputElement(pickerNo)
{
   var result = '';
   //get all people picker controls
   var pp = document.getElementsByClassName('ms-usereditor');
   var j = 0;
   for(var i=0; i < pp.length; i++)
   {
      //only if control id ends with _UserField
      if(pp[i].id.indexOf('_UserField', pp[i].id.length - '_UserField'.length) !== -1)
      {
         j++;
         if(j == pickerNo)
         {
            //this is the picker we are looking for
            result = pp[i];
            break;
         }
      }
   }
   return result;
}