<input type="checkbox" name="father" forcheckboxgroup="groupname1"/>

<input type="checkbox" name="son" group="groupname1"/>

<script type="text/javascript">
function CheckboxGroup(){
var arrelement = document.all;
var i=0;
while(i<arrelement.length){
var forgroupattrib = arrelement[i].getAttribute('forcheckboxgroup');
if(forgroupattrib != null && forgroupattrib != ''){
arrelement[i].setAttribute('groupmember',_getGroupMember(arrelement[i]));
if(arrelement[i].tagName.toLowerCase() == 'input' && arrelement[i].type == 'checkbox'){
arrelement[i].onclick=function(){
//----------------------Checked All------------------
var groupmember = this.getAttribute('groupmember');
var i = 0;
while(i<groupmember.length){
groupmember[i].checked = this.checked;
i++;
}
//---------------------------------------------------
}
}
_setState(arrelement[i]);
}
i++;
}
}

function _getGroupMember(o){
var groupname = o.getAttribute('forcheckboxgroup');
var items = new Array;
var inputs = document.getElementsByTagName('input');
var i=0;
while(i<inputs.length){
if(inputs[i].type == 'checkbox'){
var groupattrib = inputs[i].getAttribute('group');
if(groupattrib == groupname){
items[items.length] = inputs[i];
var master = inputs[i].getAttribute('groupmaster');
if (master == null) {
master = new Array;
master[0] = o.uniqueID;
inputs[i].setAttribute('groupmaster', master);
}
else{
master[master.length] = o.uniqueID;
}
inputs[i].onpropertychange = function(){
if (event.propertyName == 'checked') {
var arro = this.getAttribute('groupmaster');
var i = 0;
while (i < arro.length) {
_setState(document.getElementById(arro[i]));
i++;
}
}
}
}
}
i++;
}
return items;
}

function _setState(o){
var master = o;
if(master!=null){
var chkselall = true;
var chknosel = true;
var groupmember = master.getAttribute('groupmember');
var i = 0;
while(i<groupmember.length){
if(chkselall)chkselall = groupmember[i].checked;
if(chknosel)chknosel = !groupmember[i].checked;
i++;
}
if(master.tagName.toLowerCase() == 'input'&&master.type=='checkbox'){
if (chkselall) {
master.indeterminate = false;
master.checked = true;
}
if (chknosel) {
master.indeterminate = false;
master.checked = false;
}
if(!chkselall&&!chknosel)master.indeterminate = true;
}
else{
master.disabled = chknosel;
}
}
}

window.attachEvent('onload',CheckboxGroup);
</script>