Question

鉴于一年零一个月，我想确定该月第三个星期五的日期。我如何利用moment.js来确定这个？

E.g。 October 2015 => 16th October 2015

Answer 1

将年份和月份作为整数并假设星期五是您所在地区的星期五（星期一是一周的第一天），您可以：

function getThirdFriday(year, month){
    // Convert date to moment (month 0-11)
    var myMonth = moment({year: year, month: month});
    // Get first Friday of the first week of the month
    var firstFriday = myMonth.weekday(4);
    var nWeeks = 2;
    // Check if first Friday is in the given month
    if( firstFriday.month() != month ){
        nWeeks++;
    }
    // Return 3rd Friday of the month formatted (custom format)
    return firstFriday.add(nWeeks, 'weeks').format("DD MMMM YYYY");
}

如果您将月份和年份作为字符串，则可以使用moment parsing functions代替对象表示法，因此您将拥有：

var myMonth = moment("October 2015", "MMMM yyyy");

如果星期五不是一周中的第五天（索引为4的那一天），您可以使用moment.weekdays()

获取正确的索引

Answer 2

基于以上（1和2）的答案，

我对该函数进行了广义化，因此它可以返回给定日期的任何工作日或任何一周。

var getNthWeekday = function(baseDate, weekth, weekday){

    // parse base date
    var date = moment(baseDate);
    var year = date.year();
    var month = date.month();

    // Convert date to moment (month 0-11)
    var myMonth = moment({year: year, month: month});

    // assume we won't have to move forward any number of weeks
    var weeksToAdvance = weekth-1;

    // Get first weekday of the first week of the month
    var firstOccurranceOfDay = myMonth.weekday(weekday);

    // Check if first weekday occurrance is in the given month
    if( firstOccurranceOfDay.month() != month ){
        weeksToAdvance++;
    }

    // Return nth weekday of month formatted (custom format)
    return firstOccurranceOfDay.add(weeksToAdvance, 'weeks');

}

Answer 3

基于@VincenzoC。

这使我可以发送和接收回信。


let getThirdFriday: function(mDate) {
  // Based on https://stackoverflow.com/a/34278588

  // By default we will need to add two weeks to the first friday
  let nWeeks = 2,
  month = mDate.month();

  // Get first Friday of the first week of the month
  mDate = mDate.date(1).day(5);

  // Check if first Friday is in the given month
  //  it may have gone to the previous month
  if (mDate.month() != month) {
    nWeeks++;
  }

  // Return 3rd Friday of the month formatted (custom format)
  return mDate.add(nWeeks, 'weeks');
}

然后我可以这样称呼它：

let threeMonth = getThirdFriday(
                                  moment()
                                  .add(3, 'months')
                         ).format("YYYY-MM-DD");

确定给定月份和年份的第三个星期五

3 个答案: