请问我这个封装的时间函数怎么实现倒计时的功能？
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>时间戳转化函数</title>
</head>
<body>
</body>
<script type="text/javascript">
//日期格式化年月日时分秒函数
var formatTimeToDate = function (time) {
return new Date(time).format("yyyy-MM-dd hh:mm:ss");
};
//日期格式化年月日时
var formatTimeToDay = function (time) {
return new Date(time).format("yyyy-MM-dd");
};
Date.prototype.format = function (format) {
var date = {
"M+": this.getMonth() + 1,
"d+": this.getDate(),
"h+": this.getHours(),
"m+": this.getMinutes(),
"s+": this.getSeconds(),
"q+": Math.floor((this.getMonth() + 3) / 3),
"S+": this.getMilliseconds()
};
if (/(y+)/i.test(format)) {
format = format.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
}
for (var k in date) {
if (new RegExp("(" + k + ")").test(format)) {
format = format.replace(RegExp.$1, RegExp.$1.length == 1
? date[k] : ("00" + date[k]).substr(("" + date[k]).length));
}
}
return format;
};
console.log(formatTimeToDate(1532156400000))
console.log(formatTimeToDay(1532156400000))
</script>
</html>
