Js 通过attachEvent增加事件

function addEvent(elem, type, hdl){
    if (elem.addEventListener) { 
	    elem.addEventListener(type, hdl, false);
    } else if (elem.attachEvent) { 
        elem.attachEvent("on" + type, hdl);
    } else { 
        elem["on" + type] = hdl;
    }
}
var elem = document.getElementById('t1');
 elem.setAttribute("title","ttttt");
 addEvent(elem, 'click', b);
//window.onload=function (){
//document.getElementById('t1').attachEvent("onclick", function (){alert('abc')});
 //addEvent(elem, 'click', b);
//}
function b()
{
alert('gg');
}