var wrapCtrlName="ctl00_header_control_";
var txtStart=document.getElementById(wrapCtrlName+"txtStartDate");
var txtEnd=document.getElementById(wrapCtrlName+"txtEndDate");
var ddlDateOption=document.getElementById(wrapCtrlName+"ddlDateOption");

function onDateOptionChange(){
    var idx = ddlDateOption.options[ddlDateOption.selectedIndex].value;
    var dateobj = new Date();
    var startdate=new Date();
    var enddate=new Date();
    switch(idx){
        //cette semaine
//        case "0":
//            enddate.setDate(dateobj.getDate()+12);
//            break;
        //aujourdd'hui
        case "1":
            break;
        //demain
        case "2":
            startdate.setDate(startdate.getDate()+1);
            enddate=startdate;
            break;
        //Ce week-end
        case "3":
            startdate.setDate(dateobj.getDate()+(5-dateobj.getDay()));
            enddate.setDate(dateobj.getDate()+(7-dateobj.getDay()));
            break;
    }
    //finish, apply values
    if (idx > 0 && idx <= 3)
        SetStartAndEndDate(startdate,enddate);
}

//set values to textboxs
function SetStartAndEndDate(start,end){
    txtStart.value = formatDate(start);
    txtEnd.value = formatDate(end);
}

//return a string of the date given in format dd/mm/yyyy
function formatDate(x) {
    return to2digit(x.getDate())+"/"+to2digit(x.getMonth()+1)+"/"+x.getFullYear();
}

//to convert date or month to 2 digit: "2" -> "02"
function to2digit(x){
    return(x<0||x>9?"":"0")+x
}