addEventListener高级浏览器
attachEvent IE系列
function addEvent(obj, sEv, fn)
{
if (obj.addEventListener)
{
obj.addEventListener(sEv, fn, false);
}
else
{
obj.attachEvent(‘on‘+sEv, fn);
}
}
原文：http://www.cnblogs.com/yuanyiying/p/4899098.html