Querystring Maker

I helped someone out in the JS forum and it inspired this script which is quite handy for Ajax forms. Just pass the form object and it will return a querystring to attach to a url. Careful though, querystrings have limitations on the length of the string and it varies between browsers. Maybe there is something that does this already but I don't know of it.

function buildQuery(frm)
{
var ele=frm.elements;
var len=ele.length;
var str="?";
for(var i=0;i<len;i++)
{
var c_obj=ele[i]
if(!c_obj.disabled)
{
if(c_obj.name)
{
if(c_obj.type.toLowerCase()=="radio")
{
if(c_obj.checked)
{
str+=encodeURIComponent(c_obj.name)+"="+encodeURIComponent(c_obj.value)+"&";
}
}
else if(c_obj.type.toLowerCase()=="checkbox")
{
if(c_obj.checked)
{
if(c_obj.value)
{
c_val=c_obj.value;
}
else
{
c_val="on";
}
str+=encodeURIComponent(c_obj.name)+"="+encodeURIComponent(c_val)+"&";
}
}
else if(c_obj.tagName.toLowerCase()=="select")
{
if(c_obj.options.length>0)
{
if(c_obj.multiple)
{
var opt=c_obj.options;
var len2=opt.length;
var opt_group=encodeURIComponent(c_obj.name)+"=";
for(var j=0;j<len2;j++)
{
if(opt[j].selected)
{
if(j!=0)
{
if(opt[j].value)
{
opt_group+=","+encodeURIComponent(opt[j].value);
}
else
{
opt_group+=","+encodeURIComponent(opt[j].value);
}
}
else
{
if(opt[j].value)
{
opt_group+=encodeURIComponent(opt[j].value);
}
else
{
opt_group+=encodeURIComponent(opt[j].text);
}
}
}
}
str+=opt_group+"&"
}
else
{
if(c_obj.options[c_obj.selectedIndex].value)
{
str+=encodeURIComponent(c_obj.name)+"="+encodeURIComponent(c_obj.options[c_obj.selectedIndex].value)+"&";
}
else
{
str+=encodeURIComponent(c_obj.name)+"="+encodeURIComponent(c_obj.options[c_obj.selectedIndex].text)+"&";
}
}
}
}
else
{
str+=encodeURIComponent(c_obj.name)+"="+encodeURIComponent(c_obj.value)+"&";
}
}
}
}
str=str.substring(0,str.length-1);
return str;
}