//处理浏览器之间的差异
var EventUtil = {
    addHandler: function (element, type, handler) {
        if (element.addEventListener) {
            element.addEventListener(type, handler, false); //Dom2级方法
        }
        else if (element.attachEvent) {
            element.attachEvent("on" + type, handler); //IE方法
        }
        else {
            element["on" + type] = handler; //Dom0级方法
        }
    },
    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;
        }
    },
    getEvent: function (event) {//返回对event对象的引用
        return event ? event : window.event;
    },
    getTarget: function (event) {//返回事件的目标
        return event.target || event.srcElement;
    },
    preventDefault: function (event) {//取消事件的默认行为
        if (event.preventDefault) {
            event.preventDefault();
        }
        else {
            event.returnValue = false;
        }
    },
    stopPropagation: function (event) {//阻止事件冒泡
        if (event.stopPropagation) {
            event.stopPropagation();
        }
        else {
            event.cancelBubble = true;
        }
    },
    getRelatedTarget: function (event) {
        if (event.relatedTarget) {//DOM只对于mouseout、mouseover才包含值
            return event.relatedTarget;
        }
        else if (event.toElement) {//IE mouseout
            return event.toElement;
        }
        else if (event.fromElement) {//IE mouseover
            return event.fromElement;
        }
        else {
            return null;
        }
    },
    getButton: function (event) {
        if (document.implementation.hasFeature("MouseEvents", "2.0")) {
            return event.button;
        }
        else {
            switch (event.button) {
                case 0: //表示没按下按钮
                case 1: //表示按下了主鼠标按钮
                case 3: //表示同时按下了主，次鼠标按钮
                case 5: //表示同时按下了主鼠标按钮和中间的鼠标按钮
                case 7: //表示同时按下了三个鼠标按钮
                    return 0;
                case 2: //表示按下了次鼠标按钮
                case 6: //表示同时按下了次鼠标按钮和中间的鼠标按钮
                    return 2;
                case 4: //表示按下了中间的鼠标按钮
                    return 1;
            }
        }
    },
    getWheelDelta: function (event) {//检测事件是否包含wheelDelta属性
        if (event.wheelDelta) {
            return (client.engine.opera && client.engine.opera < 9.5 ? -event.wheelDelta : event.wheelDelta);
        }
        else {
            return -event.detail * 40;
        }
    },
    getCharCode: function (event) {//检测charCode属性是否包含数值
        if (typeof event.charCode == "number") {
            return event.charCode;
        }
        else {
            return event.keyCode;
        }
    }

}