var attendanceArray = JSON.parse(xmlhttp.responseText);
    var attendanceIndex=0;
    var attendanceCell="";
    var oddEven=0;
	for(var i=0;i<PresenzeOperatori.length;i++){
        if (pariodispariPresenze === 0 ){
            pariodispariPresenze = 1;
        }
        else{
            pariodispariPresenze =	0;
        }
        attendanceIndex= "rp" + i;
        var attendanceTableHead= document.createElement("div");
        attendanceTableHead.id = attendanceIndex;
        attendanceTableHead.className = "attendanceRow";
        attendanceTableHead.className += " rppd" + oddEven;
        document.getElementById("example_id").appendChild(attendanceTableHead);

		/*fetch id column -->and here the for loop does not iterate anything at all*/
		attendanceCell= attendanceIndex + "clp1";

		attendanceTableHead= document.createElement("div");
		attendanceTableHead.id = attendanceCell;
		var row= document.createTextNode(attendanceArray [i].id_operatore);
		attendanceTableHead.appendChild(row);
		attendanceTableHead.style.visibility="hidden";
		document.getElementById(attendanceIndex).appendChild(attendanceTableHead);

	}