下面是改变时间形式的函数，请问下怎么封装才能处理任意时间的形式，怎么加入参数？

function myFunction(){

   var a = new Date(),

    weeks = ["日","一","二","三","四","五","六"],

    week = a.getDay(),

    month = a.getMonth()+1,

    date = a.getDate(),

    year = a.getFullYear(),

    hour = a.getHours(),

    minute = a.getMinutes(),

    second = a.getSeconds();

    return document.write("今天是"+year+"年"+month+"月"+date+"日"+"星期"+weeks[week]+"<br>"+hour+":"+minute+":"+second);

    }

    myFunction();