跨浏览器的事件对象

var EventUtil = {
            addHandler: function(element,type,handler){//添加事件
                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){//获得事件对象
                return event || window.event;
            },
            getTarget: function(event){//获得事件元素
                return event.target || event.srcElement;
            },
            preventDefault: function(){//取消默认事件行为
                if (event.preventDefault)
                {
                    event.preventDefault();
                }else {
                    event.returnValue = false;
                }
            },
            removeHandler: function(element,type,handler){//取消事件
                if (element.removeEventListener)
                {
                    element.removeEventListener(type,handler,false)
                }else if (element.dettchEvent)
                {
                    element.dettchEvent('on'+type,handler);
                }else {
                    element['on'+type] = null;
                }
            },
            stopPropagation: function(event){//取消冒泡机制
                if (event.stopPropagation)
                {
                    event.stopPropagation();
                }else {
                    event.cancleBubble = true;
                }
            },
            getRelatedTarget: function(event){
                if (event.relatedTarget)
                {
                    return event.relatedTarget;//标准下返回相关元素
                }else if (event.toElement)
                {
                    return event.toElement;//mouseout事件触发，保存相关元素
                }else if (event.fromElement)
                {
                    return event.fromElement;//mouseover事件触发，保存相关元素
                }
            },
            getButton: function(event){//鼠标按钮兼容
                if (document.implementation.hasFeature('MouseEvents','2.0'))//标准下
                {
                    return event.button;
                }else {
                    switch (event.button)//非标准下
                    {
                    case 0:
                    case 1:
                    case 3:
                    case 5:
                    case 7:
                        return 0;
                    case 2:
                    case 6:
                        return 2;
                    case 4:
                        return 1;
                    }
                }
            },
            getWheelDelta: function(event){//滚轮事件兼容
                //所以要兼容，写两个函数函数
                //client的兼容性必须先写出来
                if (event.wheelDelta)
                {
                    /*
                        兼容opear9.5以前版本的正负相反，mousewheel
                    */
                    return (window.client.engine.opera && window.client.engine.opera < 9.5 ? -event.wheelDelta : event.wheelDelta);
                }else {
                    /*
                        兼容firefox正负和3的倍数的问题，DOMMouseScroll
                    */
                    return -event.detail*40;
                }
            },
            getCharCode: function(event){//键盘事件兼容
                if (typeof event.charCode == 'number')//首先检测按键有没有代表的字符，如果没有就没有charCode，为undefined
                {
                    return event.charCode;
                }else {
                    return event.keyCode
                }
            }
        }

首先要用EventUtil.getEvent(event);获得统一的event对象