计算多选框打勾的数目

<input type="checkbox" value="${goodsInfo.id}" name="id" <c:if test="${goodsInfo.checked}"> checked</c:if> onclick="selectGoods(this)">

function selectGoods(checkBoxObj){
if(checkBoxObj.checked){
count++;
}else{
count--;
}

<input type="checkbox value="checkbox1" name="checkbox">
<input type="checkbox value="checkbox2" name="checkbox">
function getcheck(){
var x=document.getElementsByName("checkbox");

for (var i=0;i<x.length;i++)
{
alter(x[i].value +" is checked!");
}