JS中时间戳转日期格式（YYYY-MM-dd HH:mm:ss）

function formatUnixtimestamp (unixtimestamp){
var unixtimestamp = new Date(unixtimestamp*1000);
var year = 1900 + unixtimestamp.getYear();
var month = "0" + (unixtimestamp.getMonth() + 1);
var date = "0" + unixtimestamp.getDate();
var hour = "0" + unixtimestamp.getHours();
var minute = "0" + unixtimestamp.getMinutes();
var second = "0" + unixtimestamp.getSeconds();
return year + "-" + month.substring(month.length-2, month.length)  + "-" + date.substring(date.length-2, date.length)
+ " " + hour.substring(hour.length-2, hour.length) + ":"
+ minute.substring(minute.length-2, minute.length) + ":"
+ second.substring(second.length-2, second.length);
}