javascript日期转换 时间戳转日期格式

Date.prototype.format = function(format) 
{ 
var o = 
{ 
"M+" : this.getMonth()+1, //month 
"d+" : this.getDate(), //day 
"h+" : this.getHours(), //hour 
"m+" : this.getMinutes(), //minute 
"s+" : this.getSeconds(), //second 
"q+" : Math.floor((this.getMonth()+3)/3), //quarter 
"S" : this.getMilliseconds() //millisecond 
} 

if(/(y+)/.test(format)) 
{ 
format = format.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length)); 
} 

for(var k in o) 
{ 
if(new RegExp("("+ k +")").test(format)) 
{ 
format = format.replace(RegExp.$1, RegExp.$1.length==1 ? o[k] : ("00"+ o[k]).substr((""+ o[k]).length)); 
} 
} 
return format; 
} 
var testDate = new Date( 1320336000000 );//这里必须是整数，毫秒 
var testStr = testDate.format("yyyy年MM月dd日hh小时mm分ss秒"); 
var testStr2 = testDate.format("yyyyMMdd hh:mm:ss"); 
alert(testStr + " " + testStr2);