事件在不同浏览器需要兼容性处理，现封装起来，便于日后使用和学习。

var EventUtil = {
    //添加事件处理
    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;
        }
    },
    //获得事件对象
    getEvent: function(event) {
        return event? event : window.event;
    },
    //获取事件目标
    getTarget: function(event) {
        return event.target || event.srcElement;
    },
    //取消事件默认行为
    preventDefault: function(event) {
        if(event.preventDefault()) {
            event.preventDefault();
        }else{
            event.returnValue = false;
        }
    },
    //移除事件
    removeHandler: function() {
        if(element.removeEventListener) {
            element.removeEventListener(type, handler, false);
        }else if(element.detachEvent){
            element.detachEvent("on" + type, handler);
        }else{
            element["on" + type] = null;
        }
    },
    //阻止事件冒泡
    stopPropagation: function(event) {
        if(event.stopPropagation) {
            event.stopPropagation();
        }else{
            event.canceBubble = true;
        }
    },
    //获取相关元素，一般是mouseover,mouseout,focus等
    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;
        }
    },
    //获取按键码
    getCharCode: function(event) {
        return (typeof event.charCode == 'number' ? event.charCode : event.keyCode);
    },
    //获取剪切板数据
    getClipboardText: function(event) {
        var getClipboardData = window.clipboardData || event.clipboardData;
        return clipboardData.getData("text");
    }

}