function formatDate(now) { 
var year=now.getYear(); 
var month=now.getMonth()+1; 
var date=now.getDate(); 
var hour=now.getHours(); 
var minute=now.getMinutes(); 
var second=now.getSeconds(); 
return "20"+year+"-"+month+"-"+date+" "+hour+":"+minute+":"+second; 
} 

var d=new Date(1230999938); 
alert(formatDate(d));

字符窜拼接年月日