calculate checkbox array length using document.getElementById in javascript

I want to calculate the length of a checkbox ar开发者_如何学JAVAray using document.getElementById('test') function.

I have an array whose id is test and lenght I want calculating checkbox array length using document.getElementById('test') strictly.

Name and ID are two Different attributes whose purpose is differently intended in DOM. Name can be associated with Group of Elements whose behavior is common say radioButtons and Checkboxes, and drowdown where ID is the one through which U can uniqly identify an element from HTML document.

So, In particular page Arraylengh of elements whose id is "test" is always 1.

var myChckboxList=document.formName.test;

now myChckboxList.length will give you the length of the array

However there is a strange behaviour-if the length is 1 then this value becomes 'undefined'