How to get the value of the PeopleEditor in SharePoint 2013

I need to get the value of the PeoplesEditor using javascrit and jquery. following this article : http://ift.tt/1xHQMeH

I did exactely the same but i allways get the undefined value : this is the html code :

<SharePoint:PeopleEditor AllowEmpty="true" ID="docReviewerUser"                            
            runat="server" MultiSelect="false" SelectionSet="User" Width="300px" /> 

and this is the javascript :

var html = $("#ctl00_PlaceHolderMain_docReviewerUser_upLevelDiv");
    var DocReviewerLoginName = $("#divEntityData", html).attr("key");

DocReviewerLoginName = undefined .

anyideas best regards