跨浏览器的事件处理方法(Professional JavaScript for Web Developers)

var EventUtil = {
            addHandler: function (element, type, handler) {
                if (element.addEventListener) {
                    element.addEventListener(type, handler, false);
                } else if (element.attachEvent) {
                    element.attachEvent("on" + type, handler);
                } else {
                    element["on" + type] = handler;
                }
            },
            getEvent: function (event) {
                return event ? event : window.event;
            },
            getTarget: function (event) {
                return event.target || event.srcElement;
            },
            preventDefault: function (event) {
                if (event.preventDefault) {
                    event.preventDefault();
                } else {
                    event.returnValue = false;
                }
            },
            removeHandler: function (element, type, handler) {
                if (element.removeEventListener) {
                    element.removeEventListener(type, handler, false);
                } else if (element.detachEvent) {
                    element.detachEvent("on" + type, handler);
                } else {
                    element["on" + type] = null;
                }
            },
            getRelatedTarget: function (event) {
                if (event.relatedTarget) {
                    return event.relatedTarget;
                } else if (event.toElement) {
                    return event.toElement;
                } else if (event.fromElement) {
                    return event.fromElement;
                } else {
                    return null;
                }
            },
            stopPropagation: function (event) {
                if (event.stopPropagation) {
                    event.stopPropagation();
                } else {
                    event.cancelBubble = true;
                }
            }
        };