//层全选与反选
function uncheckGrp(grp_id)
{
document.getElementById(grp_id).checked = document.getElementById(grp_id).checked&0;
}
function selectGroup(div_id,grp_id){
var g_div = document.getElementById(div_id);
var grp = document.getElementById(grp_id);
var eles = g_div.getElementsByTagName("input");
for(var i=0;i<eles.length;i++){
if(eles[i].disabled==false) eles[i].checked=grp.checked;
}
}
<input id="check_grp" type="checkbox" onClick="selectGroup('c_','check_grp');" />全选</h4>
<div id="c_"></div>