function checkform() {
var el = document.forms[0].elements;
for(var i = 0 ; i < el.length ; ++i) {
if(el[i].type == "radio") {
var radiogroup = el[el[i].name];
var itemchecked = false;
for(var j = 0 ; j < radiogroup.length ; ++j) {
if(radiogroup[j].checked) {
itemchecked = true;
break;
}
}
if(!itemchecked) {
alert("Please select a size.");
if(el[i].focus)
el[i].focus();
return false;
}
}
}
return true;
}