//将时间戳格式化

function getMyDate(time){

    if(typeof(time)=="undefined"){

        return "";

    }

    var oDate = new Date(time),

     oYear = oDate.getFullYear(),

     oMonth = oDate.getMonth()+1,

     oDay = oDate.getDate(),

     oHour = oDate.getHours(),

     oMin = oDate.getMinutes(),

     oSen = oDate.getSeconds(),

     oTime = oYear +'-'+ getzf(oMonth) +'-'+ getzf(oDay) +' '+ getzf(oHour) +':'+ getzf(oMin) +':'+getzf(oSen);//最后拼接时间  

     return oTime;

    };

     //补0操作,当时间数据小于10的时候，给该数据前面加一个0

    function getzf(num){

        if(parseInt(num) < 10){

            num = '0'+num;

        }

        return num;

    }

function getNowFormatDate() {

    var date = new Date();

    var seperator1 = "-";

    var seperator2 = ":";

    var month = date.getMonth() + 1;

    var strDate = date.getDate();

    if (month >= 1 && month <= 9) {

        month = "0" + month;

    }

    if (strDate >= 0 && strDate <= 9) {

        strDate = "0" + strDate;

    }

    var currentdate = date.getFullYear() + seperator1 + month + seperator1 + strDate

            + " " + date.getHours() + seperator2 + date.getMinutes()

            + seperator2 + date.getSeconds();

    return currentdate;

}

 function getNowFormatDate() {

        var date = new Date();

        var seperator1 = "-";

        var year = date.getFullYear();

        var month = date.getMonth() + 1;

        var strDate = date.getDate();

        if (month >= 1 && month <= 9) {

            month = "0" + month;

        }

        if (strDate >= 0 && strDate <= 9) {

            strDate = "0" + strDate;

        }

        var currentdate = year + seperator1 + month + seperator1 + strDate;

        return currentdate;

    }

//一行啊~~！TMD居然一样代码就写了

var str = "今天是星期" + "日一二三四五六".charAt(new Date().getDay());

console.log(str);

//计算日期相减天数

    function DateMinus(time){

      var sdate = new Date(time);

      var now = new Date();

      var days = now.getTime() - sdate.getTime();

      var day = parseInt(days / (1000 * 60 * 60 * 24));

      return day;

    }

    let number = DateMinus();

    console.log(number)

time 只要是符合时间格式的字符串就行。比如：

var sdate = new Date("Sep 22, 2018 12:00:00 AM");

var sdate = new Date("2018-8-09");