时间戳转formdate格式 13 || 16 位

    function timeStampToFormdate(timestamp) {
        if (!timestamp) {
            return ''
        }
        var date = timestamp.toString().length == "13" ? new Date(timestamp) : new Date(timestamp * 1000); //时间戳为10位需*1000，时间戳为13位的话不需乘1000
        var Y = date.getFullYear() + "-";
        var M = (date.getMonth() + 1 < 10 ? "0" + (date.getMonth() + 1) : date.getMonth() + 1) + "-";
        var D = (date.getDate() < 10 ? '0' + date.getDate() : date.getDate());
        var h = date.getHours() < 10 ? "0" + date.getHours() + ":" : date.getHours() + ":";
        var m = date.getMinutes() < 10 ? "0" + date.getMinutes() + ':' : date.getMinutes() + ":";
        var s = date.getSeconds() < 10 ? "0" + date.getSeconds() : date.getSeconds();
        return Y + M + D + ' ' + h + m + s;
    }
    console.log(timeStampToFormdate(new Date().getTime()));

获取距离当前时间多少天前的时间

 function manyDayBeforeNowDay(days) {
        if (days * 1) {
            return timeStampToFormdate(new Date().getTime() - days * 60 * 60 * 24 * 1000)
        } else {
            return ''
        }
    }
    console.log(manyDayBeforeNowDay(2));

时间格式化返回年月日时分秒 格式自己拼

/**
*如果没有传入时间，就返回当前时间的格式化数据
*/
function dateFormat(date) {
!date && date=new Date();
  if (date) {
    let newDate = new Date(date);
    let n = newDate.getFullYear();
    let y = (newDate.getMonth() + 1 < 10 ? '0' + (newDate.getMonth() + 1) : newDate.getMonth() + 1);
    let r = (newDate.getDate() < 10 ? '0' + newDate.getDate() : newDate.getDate());
    let s = (newDate.getHours() < 10 ? '0' + newDate.getHours() : newDate.getHours());
    let f = (newDate.getMinutes() < 10 ? '0' + newDate.getMinutes() : newDate.getMinutes());
    let m = (newDate.getSeconds() < 10 ? '0' + newDate.getSeconds() : newDate.getSeconds());
    let format = {
      n: n,
      y: y,
      r: r,
      s: s,
      f: f,
      m: m,
    }
    return format
  }
}

获取当前星期几

function getWeekDate() {
  var now = new Date();
  var day = now.getDay();
  var weeks = new Array(
    "星期日",
    "星期一",
    "星期二",
    "星期三",
    "星期四",
    "星期五",
    "星期六"
  );
  var week = weeks[day];
  return week;
}

根据当前年的第几天 获取所在的日期

/**
 * @param {Number} year 哪年
 * @param {Number} day  哪天
 */
function dayToMD(year, day) {
  if (year && day && day < 367) {
    var isrunnian = (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
    var rules = [31, isrunnian ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
    for (var i = 0; i < rules.length; i++) {
      if (rules[i] >= day) {
        return (i + 1 < 10 ? ("0" + (i + 1)) : (i + 1)) + '-' + (day < 10 ? ("0" + day) : day);
      }
      day -= rules[i];
    }
  }
}

获取所在周

记录一下 ，计算规则比较怪。产品这么要求，╮(╯▽╰)╭

/**
 * 获取当前天所在的周
 * 规则：按照日历上一行为一周。以当前年第一个周一所在的日期为当前年的起点
 * 如果当前日期>=起点，计算公式：Math.ceil((当前天数-(起点-1))/7)
 * 如果当前日期<起点 ，计算公式：Math.ceil((上一年的天数-(上一年起点-1)+当前日期天数)/7)
 * 返回结果 2020-1  2020年第几周
 * 头秃
 */

function weekFilter() {
  function yearDays(leapY) {
    var strleapYis =
      (leapY % 4 == 0 && leapY % 100 != 0) || leapY % 400 == 0;
    if (strleapYis) {
      strleapYis = 366;
    } else {
      strleapYis = 365;
    }
    return strleapYis;
  }
  function getWeekDay(year) {
    var d = new Date();
    d.setFullYear(year, 0);
    for (var i = 1; i <= 31; i++) {
      d.setDate(i);
      if (d.getDay() == 1) break;
    }
    d.setFullYear(year, 0, i);
    // return year + "-" + "01-" + (i >= 10 ? i :( "0" + i));
    return i;
  }
  let nowDay = Math.ceil(
    (new Date() - new Date(new Date().getFullYear().toString())) /
      (24 * 60 * 60 * 1000)
  );
  let nowYear = new Date().getFullYear();
  let nowWeek;
  if (nowDay >= getWeekDay(nowYear)) {
    nowWeek = Math.ceil((nowDay - (getWeekDay(nowYear) - 1)) / 7);
    return `${nowYear}-${nowWeek}`
  } else {
    nowWeek = Math.ceil(
      (yearDays(nowYear - 1) - (getWeekDay(nowYear - 1) - 1) + nowDay) / 7
    );
    return `${nowYear - 1}-${nowWeek}`
  }
}