Sum column value with javascript

Hi guys ,

i want to sum a column with javascript after a query.. This is my query:

 var queryTotalTime = "<View><Query><Where><IsNotNull><FieldRef Name='Estimated_x0020_Time_x0020__x002'/></IsNotNull></Where></Query></View>";

 var querySpentTime = "<View><Query><Where><IsNotNull><FieldRef Name='Real_x0020_spent_x0020_time' /></IsNotNull></Where></Query></View>";

		    var siteUrl = window.location.protocol + "//" + window.location.host;
		    var clientContext = SP.ClientContext.get_current();
		    var oList = clientContext.get_web().get_lists().getByTitle('Task');

		    var MyTotalQuery = new SP.CamlQuery();
		    MyTotalQuery.set_viewXml(queryTotalTime);
		    myTotalTimeItems = oList.getItems(MyTotalQuery);

I have to iterate myTotalTimesItems?how?

Thank you!