//Get Logged in CRM user ID
  function GetUserId()
  {
  try
  {
  var Command = new RemoteCommand("SystemUser", "WhoAmI", "/MSCRMServices/");
  var Result = Command.Execute();
  
  if (Result.Success)
  {
  return Result.ReturnValue.UserId;
  }
  }
  catch(e)
  {
  alert("Error while fetching User details.");
  }
  return null;
  }
  
  

  
  function GetLoggedUserName()
  {
                   //Create the XML that will fetch the required info.
                   //You can inspect this web service call using a tool called FIDDLER.
                   var XMLRequest = "" + 
                   "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + 
                   "<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">" + GenerateAuthenticationHeader() +
                   " <soap:Body>" + 
                   " <RetrieveMultiple xmlns=\"http://schemas.microsoft.com/crm/2007/WebServices\">" + 
                   " <query xmlns:q1=\"http://schemas.microsoft.com/crm/2006/Query\" xsi:type=\"q1:QueryExpression\">" + 
                   " <q1:EntityName>systemuser</q1:EntityName>" + 
                   " <q1:ColumnSet xsi:type=\"q1:ColumnSet\">" + 
                   " <q1:Attributes>" + 
                   " <q1:Attribute>systemuserid</q1:Attribute>" + 
                   " <q1:Attribute>fullname</q1:Attribute>" + 
                   " </q1:Attributes>" + 
                   " </q1:ColumnSet>" + 
                   " <q1:Distinct>false</q1:Distinct>" + 
                   " <q1:Criteria>" + 
                   " <q1:FilterOperator>And</q1:FilterOperator>" + 
                   " <q1:Conditions>" + 
                   " <q1:Condition>" + 
                   " <q1:AttributeName>systemuserid</q1:AttributeName>" + 
                   " <q1:Operator>EqualUserId</q1:Operator>" + 
                   " </q1:Condition>" + 
                   " </q1:Conditions>" + 
                   " </q1:Criteria>" + 
                   " </query>" + 
                   " </RetrieveMultiple>" + 
                   " </soap:Body>" + 
                   "</soap:Envelope>" + 
                   "";
  
  
  
                   try
                   {
  
                   //Create Http request object
                   var xmlHttpRequest = new ActiveXObject("Msxml2.XMLHTTP");
                   xmlHttpRequest.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);
                   xmlHttpRequest.setRequestHeader("SOAPAction","http://schemas.microsoft.com/crm/2007/WebServices/RetrieveMultiple");
                   xmlHttpRequest.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
                   xmlHttpRequest.setRequestHeader("Content-Length", XMLRequest.length);
                   xmlHttpRequest.send(XMLRequest);
  
                   //Store the response which would be XML
                   var Result = xmlHttpRequest.responseXML;
  
                   /*
                                    The return is of type "BusinessEntity" if you were using similar code one server side.
                                    Hence we need to select node of type "BusinessEntity"
  
                                    In our case It should be not more one than one node
                   */
                   var BusinessEntityNodes = Result.selectNodes("//RetrieveMultipleResult/BusinessEntities/BusinessEntity");
  
                   // Check If data was retrived
                   if (BusinessEntityNodes.length != 0)
                   {
  
                                    
                                    var BusinessEntityNode = BusinessEntityNodes[0]; 
                                    var SystemUserId = BusinessEntityNode.selectSingleNode("q1:systemuserid");
                                    var FullName = BusinessEntityNode.selectSingleNode("q1:fullname");
  
                                    
                                    var SystemUserId = (SystemUserId == null) ? null : SystemUserId.text;
                                    var FullName = (FullName == null) ? null : FullName.text;
  
                     
                    
                    }
                                    return FullName;
                   }
                   catch (e)
                   {
                                    alert(e.message);
                   }
  
                    
  
  }
  alert(GetLoggedUserName());