var?eventUtil={??
????//addHandler?添加句柄
????addHandler:function(element,type,handler){
????????if(element.addEventListener){
????????????element.addEventListener(type,handler,false);
????????}else?if(element.attachEvent){//IE
????????????element.attachEvent('on'+type,handler);
????????}else{
????????????element['on'+type]=handler;
????????????//?element['onclick']===element.onclick
????????}
????},
?????//?刪除句柄
????removeHandler:function(element,type,handler){
????????if(element.removeEventListener(){
????????????element.removeEventListener(type,handler,false);
????????}else?if(element.detachEvent){//IE
????????????element.detachEvent('on'+type,handler);
????????}else{
????????????element['on'+type]=null;
????????}
????}
}

eventUtil.addHandler(btn3,'click',showMessage);