javascript multibox 全选

function allselect()
{
try{
var checkedcount=0;
for(var i=0;i<form1.orgids.length;i++)
{
if(form1.orgids[i].checked)
checkedcount++;
}

if(checkedcount==form1.orgids.length)
{
for(var i=0;i<form1.orgids.length;i++)
{
form1.orgids[i].checked=false;
}
}
else
{
for(var i=0;i<form1.orgids.length;i++)
{
form1.orgids[i].checked=true;
}
}
if(form1.orgids.checked==true)
form1.orgids.checked=false;
else
form1.orgids.checked=true;
}catch(ex){}
}

<span style="cursor:hand" onclick="allselect()">(全选)</span>
<logic:iterate id="result" name="zclist" indexid="ind">
<html:multibox property="orgids"><bean:write name="result" property="someproperty"/></html:multibox>
</logic:iterate>