cross browser addEvenlistener

var addListener = function() {
    if ( window.addEventListener ) {
        return function(el, type, fn) {
            el.addEventListener(type, fn, false);
        };
    } else if ( window.attachEvent ) {
        return function(el, type, fn) {
            var f = function() {
                fn.call(el, window.event);
            };
            el.attachEvent('on'+type, f);
        };
    } else {
        return function(el, type, fn) {
            element['on'+type] = fn;
        }
    }
}();