select 2 or more checkbox count js if function this check box code example
Example: how to numbers by checked in checkbox in javascript
function checkboxes(){
var inputElems = document.getElementsByTagName("input"),
count = 0;
for (var i=0; i<inputElems.length; i++) {
if (inputElems[i].type === "checkbox" && inputElems[i].checked === true){
count++;
alert(count);
}
}}