Check/Uncheck all checkboxes of a gridview in javascript

This is asp.net article shows how to Check/Uncheck select/deselect all child checkboxes of a table or gridview or datagrid as header checkbox  Check/Uncheck select/deselect in asp.net through JavaScript.

<asp:CheckBox ID="CheckBox1" onchange="SelectAllCheckboxes(this)" runat="server" />

function SelectAllCheckboxes(Chk) {

                    var IsChecked = Chk.checked;

                    var Chk = Chk;

         var Parent = document.getElementById('gvUsers');

                    var items = Parent.getElementsByTagName('input');

                    for (i = 0; i < items.length; i++) {

                        if (items[i].id != Chk && items[i].type == "checkbox") {

                            if (items[i].checked != IsChecked) {

                                items[i].click();

                            }

                        }

                    }

                }

//Or use this if your checkboxes in first column of gridview/table

<asp:CheckBox ID="CheckBox1" onchange="SelectAllCheckboxes(this)" runat="server" />

function SelectAllCheckboxes(Chk) {

                    var IsChecked = Chk.checked;

                    var Chk = Chk;

                    var  Parent = document.getElementById('gvUsers');

                    for (i = 0; i < Parent.rows.length; i++) {

                        var tr = Parent.rows[i];

                        //var td = tr.childNodes[0];

                        var td = tr.firstChild;

                        var item = td.firstChild;

                        if (item.id != Chk && item.type == "checkbox") {

                            if (item.checked != IsChecked) {

                                item.click();

                            }

                        }

                    }

                }