复选框全选

<form name=hrong>
<input type=checkbox name=All onclick="checkAll('mm')">全选

<br/>
<input type=checkbox name=mm onclick="checkItem

('All')"><br/>
<input type=checkbox name=mm onclick="checkItem

('All')"><br/>
<input type=checkbox name=mm onclick="checkItem

('All')"><br/>
<input type=checkbox name=mm onclick="checkItem

('All')"><br/>
<input type=checkbox name=mm onclick="checkItem

('All')"><br/><br/>

<input type=checkbox name=All2 onclick="checkAll('mm2')">全

选<br/>
<input type=checkbox name=mm2 onclick="checkItem

('All2')"><br/>
<input type=checkbox name=mm2 onclick="checkItem

('All2')"><br/>
<input type=checkbox name=mm2 onclick="checkItem

('All2')"><br/>
<input type=checkbox name=mm2 onclick="checkItem

('All2')"><br/>
<input type=checkbox name=mm2 onclick="checkItem

('All2')"><br/>

</form>

<script LANGUAGE="javascript">
function checkAll(str)
{
  var a = document.getElementsByName(str);
  var n = a.length;
  for (var i=0; i<n; i++)
  a[i].checked = window.event.srcElement.checked;
}
function checkItem(str)
{
  var e = window.event.srcElement;
  var all = eval("document.hrong."+ str);
  if (e.checked)
  {
    var a = document.getElementsByName(e.name);
    all.checked = true;
    for (var i=0; i<a.length; i++)
    {
      if (!a[i].checked){ all.checked = false; break;}
    }
  }
  else all.checked = false;
}
</script>