日期类型

     一个date对象是一个时间点的概念，就是对从一个固定起点时刻（1970-1-1日的0点0分0秒）到某个时刻所走过的毫秒数的封装；

方法:

   var now=new Date();

格式化输出一个Date对象

var weekDay=["星期日","星期一","星期二","星期三","星期四","星期五","星期六"]

function  moz(num){   return ( (num<10)?  "0":"")+num;}function formatDate() {    return ""+d.getFullYear()+      "-"+moz(d.getMonth())+     "-"+moz(d.getDate())+     " "+moz(d.getHours())+    ":"+moz(d.getMinutes())+    ":"+moz(d.getSeconds())+     " "+weekDay[d.getDay()];}