[jQuery] Return data from dimensions.js

[teazer]

I need to save the coordinates of a div to be able to return it to the
same location and am having problems posting the offset from
dimensions.js

This

$(".dragL").mouseup(function(e){
                var stroke = $(this).attr("id");
                var coordsB = $(this).offset({ scroll: false });
                $.post("pre_scripts.cfm", {
                coords: e.pageX +','+ e.pageY,
                coordsDiv: coordsB,
                strokeNo: stroke
                },
                function(data){
                  //alert(data);
                  var commaAt = data.indexOf(',');
                         $( '#' + data.substr(0, commaAt) ).text( 
data.substr(commaAt
+1) );
                });
        });

posts this

COORDSDIV: [object Object]
STROKENO: S2
COORDS: 122,129

How do I read [object Object]