Selecting / Deselecting all the CheckBoxes Inside a GridView

Use this javascript function in gridview for select and deselect checkbox

function chkType(chk, grd) {
    var mainChk;

    // alert (grd);
    //   alert(document.getElementById("ctl00_ContentPlaceHolder1_"+grd+"_ctl01_"+chk));

    if (document.getElementById("ctl00_ContentPlaceHolder1_" + grd + "_ctl01_" + chk) == null) {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + grd + "_ctl02_" + chk);
    }
    else {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + grd + "_ctl01_" + chk);

    }
    //if(document.getElementById("ctl00_ContentPlaceHolder1_"+grd+"_ctl01_"+chk).checked==true)
    if (mainChk.checked == true) {

        SelectAll(grd);
    }
    else {
        Deselect(grd);
        //             var id=document.getElementById("ctl00_ContentPlaceHolder1_GrdAccountType_ctl01_chkAll");
        //             id.checked = false;
    }

}


function SelectAll(Grd) {
    var i;

    var count = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd).rows.length;


    for (i = 2; i <= count; i++) {
        if (i < 10) { var id = "ctl00_ContentPlaceHolder1_" + Grd + "_ctl0" + i + "_ChkSelect"; }
        else { var id = "ctl00_ContentPlaceHolder1_" + Grd + "_ctl" + i + "_ChkSelect"; }
        var elem = document.getElementById(id);
        try {
            elem.checked = true;
            ;
        }
        catch (err) { }
    }
    var mainChk;
    if (document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl01_chkAll") == null) {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl02_chkAll");
    }
    else {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl01_chkAll");
    }
    mainChk.checked = true;

}

function Deselect(Grd) {

    var i;
    var count = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd).rows.length;
    for (i = 2; i <= count; i++) {
        if (i < 10) {
            var id = "ctl00_ContentPlaceHolder1_" + Grd + "_ctl0" + i + "_ChkSelect";

        }
        else {
            var id = "ctl00_ContentPlaceHolder1_" + Grd + "_ctl" + i + "_ChkSelect";
        }
        try {
            var elem = document.getElementById(id);
            elem.checked = false;
        }
        catch (err) {

        }

    }

    var mainChk;
    if (document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl01_chkAll") == null) {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl02_chkAll");
    }
    else {
        mainChk = document.getElementById("ctl00_ContentPlaceHolder1_" + Grd + "_ctl01_chkAll");
    }
    //if(document.getElementById("ctl00_ContentPlaceHolder1_"+grd+"_ctl01_"+chk).checked==true)
    mainChk.checked = false;
}