Checkbox Limit using dynamic field name

I found a checkbox limit javascript that works great, but I need to make it dynamic (more than one checkbox group). The original script looks like this:

function chkcontrol(j) {
var total=0;
for(var i=0; i < document.form1.ckb.length; i++){
if(document.form1.ckb[i].checked){
total =total +1;}
if(total > 3){
alert("Please Select only three") 
document.form1.ckb[j].checked = false ;
return false;
}
}
} 

Code (markup):

With the call looking like this:

><input type=checkbox name=ckb value=1 onclick=''chkcontrol(0)'';>

HTML:

I am trying to use the same script for different checkboxes... like this:

function chkcontrol(j, limit, name) {
var total=0;

for(var i=0; i < document.form1." + name + ".length; i++){
if(document.form1.name[i].checked){
total =total +1;}
if(total > limit){
alert("Please Select only " + limit) 
document.form1.name[j].checked = false ;
return false;
}
}
} 

Code (markup):

But I donot know how to get the field name to recognize in the script???

 

function chkControl(box, limit)
{
 var cbArray=box.form[box.name];
 
 for(var i=0, count=0, len=cbArray.length; i<len; i++)
  if(cbArray[i].checked)
   count++; 
   
 if(count > limit)
 {
  box.checked=false;
  alert('Check no more than '+limit);
 }    
}

Code (markup):

onclick="chkControl(this, 4)"

Code (markup):

All checkboxes must be within a form.