var spread = new GC.Spread.Sheets.Workbook($("#ss")[0]);
var activeSheet = spread.getActiveSheet();

$("#ss").click(function (e) {
     //Acquire cell index from mouse-clicked point of regular cells which are neither fixed rows/columns nor row/column headers.
     var offset = $("#ss").offset();
     var x = e.pageX - offset.left;
     var y = e.pageY - offset.top;
     var target = spread.getActiveSheet().hitTest(x, y);

     if(target &&
         (target.rowViewportIndex === 0 || target.rowViewportIndex === 1) &&
         (target.colViewportIndex === 0 || target.colViewportIndex === 1)){
         console.log("Row index of mouse-clicked cells: " + target.row);
         console.log("Column index of mouse-clicked cells: " + target.col);
     }
 });