js实现checkbox多级选择

<script type="text/javascript">

function chose(obj){
  var funid= obj.id;
  var f = window.document.sysRoleForm;
  var ele = f.elements;
  var len = funid.length;
  var lent = len/3;
  var endsub = len-3;
  var count = 0;
  var tolcount =0;

  switch(obj.checked){
case true:{

   for (var i = 0; i < ele.length; i++) {
var name = ele[i].id;
if(name.indexOf(funid)==0){
document.sysRoleForm.all(name).checked=true;
}
}
for(i=1;i<lent;i++){
var sub = funid.substring(0,endsub);
endsub=endsub-3;
   document.sysRoleForm.all(sub).checked=true;
}
break;
}
case false:{
for (var i = 0; i < ele.length; i++) {
var name = ele[i].id;
var nlen = name.length;
if(name.indexOf(funid)==0){
document.sysRoleForm.all(name).checked=false;
}
if(nlen>3){
var  subname = name.substring(0,nlen-3);
if(nlen==len && funid.indexOf(subname)==0){
count = count +1 ;
}
if(nlen==len && funid.indexOf(subname)==0 && document.sysRoleForm.all(name).checked==false){
tolcount = tolcount +1 ;
}

  }
}
if(count==tolcount && count!=0 && tolcount !=0){
subfunid = funid.substring(0,endsub)
document.sysRoleForm.all(subfunid).checked=false;
}
break;
}
}
}
</script>