如何在moment.js中获取当前月份的周数

Question

I want to get the week numbers of a particular month eg: January 2017 ,the weeknumbers in this months are [52,1,2,3,4,5] So how to get the above in an array? Thanks

Answer 1

 const firstDayOfMonth = moment(`${ year }-${ month }`, 'YYYY-MM-DD');
 const numOfDays = firstDayOfMonth.daysInMonth();
 let weeks = new Set();

 for(let i = 0; i < numOfDays; i++){
     const currentDay = moment(firstDayOfMonth, 'YYYY-MM-DD').add(i, 'days');

     weeks.add(currentDay.isoWeek());
 }

 return Array.from(weeks)

Answer 2

So more efficiently:

 const firstDayOfMonth = moment(`${ year }-${ month }`, 'YYYY-MM-DD');
 let weekIndices = [];

 let currentDay = moment(firstDayOfMonth, 'YYYY-MM-DD');
 weekIndices.push(currentDay.isoWeek());

 while(currentDay.month() === firstDayOfMonth.month()) {
     currentDay.add(1, 'weeks');
     weekIndices.push(currentDay.isoWeek());
 }

return weekIndices;

Answer 3

I know I should not, but I like this question :) can you improove this?

    function showWeeks(year, month) {

      let firstWeek = moment(new Date(year,month,1)).isoWeek();
      let lastWeek = moment(new Date(year,month+1,0)).isoWeek();

      let out = [firstWeek];
      if (firstWeek === 52 || firstWeek === 53) {
        firstWeek=0;
      }

      for ( let i = firstWeek+1; i<= lastWeek; i++) {
        out.push(i);
      }

      return out;
    }

    console.log(showWeeks(2017, 0)); // [52, 1, 2, 3, 4, 5]
    console.log(showWeeks(2021, 0)); // [53, 1, 2, 3, 4]
    console.log(showWeeks(2017, 11)); // [48, 49, 50, 51, 52]
    console.log(showWeeks(1986, 9)); // [40, 41, 42, 43, 44]