兼容各大浏览器的event获取

event:

//得到事件
function getEvent(evt){

    if (evt && typeof(evt) != "undefined") {
        var e = window.event || arguments.callee.caller.arguments[0];

        if (typeof(evt) != "undefined") {
            e = window.event || evt;
        }

        return e;
    } else {
        if(window.event)    {return window.event;}

        try {
            func = getEvent.caller;

            while(func!=null){
                var arg0=func.arguments[0];

                if(arg0){
                    if((arg0.constructor==Event || arg0.constructor ==MouseEvent
                        || arg0.constructor==KeyboardEvent)
                        ||(typeof(arg0)=="object" && arg0.preventDefault
                        && arg0.stopPropagation)){
                        return arg0;
                    }
                }

                func = func.caller;
            }
        } catch (e) {
            return null;
        }

        return null;
    }
}

target:

//获取事件操作对象
function getTarget(evt) {
    //var e = window.event || arguments.callee.caller.arguments[0]; //获取触发事件的源对象
    var e = getEvent(evt); //获取触发事件的源对象
    
    if (typeof(e) != "undefined") {
        try {
            var target =  (typeof(e.srcElement) != "undefined") && e.srcElement ? e.srcElement : e.target;
        } catch (ex) {
            target = null;
        }
        
    } else {
        target = null;
    }
    
    return target;
}

事件冒泡:

//事件冒泡
function preventEvent() {
    //取消事件冒泡
    //var e = arguments.callee.caller.arguments[0] || event; //若省略此句，下面的e改为event，IE运行可以，但是其他浏览器就不兼容
    var e = getEvent(); //获取触发事件的源对象
    
    if (e && e.stopPropagation) {
        // this code is for Mozilla and Opera
        e.stopPropagation();
    } else if (window.event) {
        // this code is for IE
        window.event.cancelBubble = true;
    } 
}