js 모양 모드에 대한 자세한 설명

function addEvent(dom,type,fn){    if(dom.addEventListener){
        dom.addEventListener(type,fn,false)
    } else if(dom.attachEvent){
        dom.attachEvent('on'+type,fn);
    } else {
        dom['on'+type]=fn;
   }
}

var myp = document.getElementById('myp');
addEvent(myp,'click',function(){
   console.log('hahah');
   })

var A={    get:function(id){
        return document.getElementById(id)
        }
    css:function(id,key,value){
        this.get(id).style[key]=value;
        }
    html:function(id,content){
        this.get(id).innerHTML=content;
        }
A.html('box','这是新添加的内容');