//事件绑定封装
function addEvent(elem, type, handle){
if(elem.addEventListener){
elem.addEventListener(type,handle,false);
}else if(elem.attachEvent){
elem.attachEvent(‘on‘+type,function(){
handle.call(elem);
});
}else{
elem[‘on‘+type] = handle;
}
}
原文：https://www.cnblogs.com/M87-A/p/11248386.html