Clear Radio Button

(function() {
 
  var currRadioRef = null;
  var currRadioVal = null;
 
  function clearRadio(event) {
    var t = event.target;
 
    if (isRadio(t)) {
      if ((currRadioRef==t) && currRadioVal) {
        t.checked = false;
        currRadioRef = null;
      }
    }
  }
 
  function getRadioState(event) {
    var t = event.target;

    if (isRadio(t)) {
      currRadioRef = t;
      currRadioVal = t.checked;
    }
  }
 
  function isRadio(ctrl) {
    return (ctrl.tagName.toUpperCase() == "INPUT" && ctrl.type == "radio");
  }
 
  document.documentElement.addEventListener("mousedown", getRadioState, true);
  document.documentElement.addEventListener("click", clearRadio, true);
 
})();