IE event listener

ieListenerEvent.js

var addEvent =  window.attachEvent||window.addEventListener;
var event = window.attachEvent ? 'onclick' : 'click';
addEvent(event, function(){
    alert('Hello!')
});

// another

if (!someElement.addEventListener) {
    _checkbox.attachEvent("onclick", setCheckedValues);
}
else {
    _checkbox.addEventListener("click", setCheckedValues, false);
}