White fill text overprint need to be select

I need your help. I am new to write the javascript.  I need to select the white text with overprint enabled (White means: C=0, M=0, Y=0, K=0).

I am writing the script but I don't it is not working properly. kindly highlight my error or advice me. 

Reference script below: 

#target illustrator-21

function fillColorOp(){

    var doc = app.activeDocument;

    doc.selection = null;

     for(var i=0; i < doc.textFrames.length; i++)

     var thisTf = doc.textFrames[i];

     {

          for ( var j = 0; j < thisTf.textRanges.length; j++ ) 

          var thisTr = thisTf.textRanges[j];

          {

              if(thisTr.characterAttributes.fillColor &&

              (Math.round(thisTr.characterAttributes.fillColor.cyan) == 0) &&

              (Math.round(thisTr.characterAttributes.fillColor.magenta) == 0) &&

              (Math.round(thisTr.characterAttributes.fillColor.yellow) == 0) &&

              (Math.round(thisTr.characterAttributes.fillColor.black) == 0) && (thisTr.characterAttributes.fillOverprint))

              {

                  thisTr.selected = true;

                  };

              };

          };

      };

  fillColorOp();

Thanks in advance

Kalaimani.S