How to get the value of the prev selected radio button

Question

Given this markup http://jsfiddle.net/ARPCw/ how can I update the total on change?

The problem is that I need the value (data-price) of the previous selected radio button, so I can subtract it to the total amount before to add the new one.

Answer 1

example fiddle: http://jsfiddle.net/ARPCw/5/

relevant js

var cb = document.getElementsByTagName('input'),
    total = document.getElementById('tprice');

for (var i = 0; i < cb.length; i++) {
    (function(c) {
       c.onclick = function() {
          var bp = 200;
          for (var i = 0; i < cb.length; i++) {
             if (!!cb[i].checked) {
               bp += +cb[i].getAttribute('data-price');  
             }
          }
          total.innerHTML = bp;
       }
    }(cb[i]))        
}