Use JS to determine if a checkbox has at least one selection

JS we know that if in the ASP, as long as Response.Write Request.Form ("Checkboxname") can determine whether there is a choice of at least one, but must be submitted before you can do so, it is necessary to contact the scripting language Js,vbs

Let's say we have a checkbox called Opthscameratyp, and we write a function to judge

function Chkcheckboxchs (Objnam) {//check if there are at least one item selected for a multiple-selection box
var obj = document.getelementsbyname (Objnam); Access to multiple marquee numbers
var objlen= obj.length; Obtain data length
var Objyn; Do you have a choice
var i;
Objyn=false;
for (i = 0;i< objlen;i++) {
if (obj [i].checked==true) {
objyn= true;
Break
}
}
return Objyn;

}

This is then invoked on the submitting program:

function Oksend ()
{
if (CHKCHSHSC (opthscameratyp) = = False) {
Alert (' Please select at least one! ');
}
Return
}

Because the checkbox has more than one name, so in JS if simple document.all.checkboxNam can not identify exactly which control, must use Document.getelementsbyname, as an array to distinguish them