js 兼容添加事件响应函数

function addEventHandler(elm,eventType,handler){
	elm=typeof elm=="string"?document.getElementById(elm):elm;
	if(elm.attachEvent){
		elm.attachEvent("on"+eventType,handler);
	}else if(elm.addEventListener){
		elm.addEventListener(eventType,handler,false);
	}else 
		return false;
}

//绑定事件 --解决this的指向问题（冯总）   暂时不理解是什么意思，在哪里能用到
CBTC.Cevent.addDomEvent = function(elem, type, fn){
    if(elem.attachEvent){
        var typeRef = "_" + type;
        if(!elem[typeRef]){
            elem[typeRef] = [];
        }
        for(var i in elem[typeRef]){
            if(elem[typeRef][i] == fn){
                return;
            }
        }
        elem[typeRef].push(fn);
        elem["on"+type] = function(){
            for(var i in this[typeRef]){
                this[typeRef][i].apply(this,arguments);
            }
        }   
    }else{
        elem.addEventListener(type,fn,false);
    }
};