js 格式化日期

Date.prototype.format = function(format) //author: meizz
{
  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 d = new Date().format("yyyyMMddhhmmss");