时间戳转换为时间 以及时间计算之后的倒计时

//将时间戳转换为时间
function formatDateTime(timeStamp) {
var date = new Date();
date.setTime(timeStamp * 1000);
var y = date.getFullYear();
var m = date.getMonth() + 1;
m = m < 10 ? ('0' + m) : m;
var d = date.getDate();
d = d < 10 ? ('0' + d) : d;
var h = date.getHours();
h = h < 10 ? ('0' + h) : h;
var minute = date.getMinutes();
var second = date.getSeconds();
minute = minute < 10 ? ('0' + minute) : minute;
second = second < 10 ? ('0' + second) : second;
return y + '-' + m + '-' + d+' '+h+':'+minute+':'+second;
};
console.log(formatDateTime(1495157126));

//倒计时

 <span class="timespan"></span>

var starttime = new Date("2017-12-28 18:39:22"); //时间一定要new Data一下
setInterval(function () {
var nowtime = new Date();
console.log(starttime)
console.log(nowtime);
var time = starttime - nowtime;
console.log(time)
var day = parseInt(time / 1000 / 60 / 60 / 24);
var hour = parseInt(time / 1000 / 60 / 60 % 24);
var minute = parseInt(time / 1000 / 60 % 60);
var seconds = parseInt(time / 1000 % 60);
$('.timespan').html(day + "天" + hour + "小时" + minute + "分钟" + seconds + "秒");
}, 1000);