The source code

    /**
     * @ignore
     *  utils for event
     * @author yiminghe@gmail.com
     */
    KISSY.add('event/dom/base/utils', function (S, DOM) {
        var EVENT_GUID = 'ksEventTargetId_1.30',
            doc = S.Env.host.document,
            simpleAdd = doc && doc.addEventListener ?
                function (el, type, fn, capture) {
                    if (el.addEventListener) {
                        el.addEventListener(type, fn, !!capture);
                    }
                } :
                function (el, type, fn) {
                    if (el.attachEvent) {
                        el.attachEvent('on' + type, fn);
                    }
                },
            simpleRemove = doc && doc.removeEventListener ?
                function (el, type, fn, capture) {
                    if (el.removeEventListener) {
                        el.removeEventListener(type, fn, !!capture);
                    }
                } :
                function (el, type, fn) {
                    if (el.detachEvent) {
                        el.detachEvent('on' + type, fn);
                    }
                };

        return {
            simpleAdd: simpleAdd,

            simpleRemove: simpleRemove,

            data: function (elem, v) {
                return DOM.data(elem, EVENT_GUID, v);
            },

            removeData: function (elem) {
                return DOM.removeData(elem, EVENT_GUID);
            }
        };

    }, {
        requires: ['dom']
    });