Finding number of days until a certain date

Question

I'm using Node.js and Moment in order to retrieve the days until the next 8th:

const getDaysTillSalary = (day) => {
    const today = moment();
    const currentDay = moment().format('D');
    let currentMonth = moment().format('M');
    let currentYear = moment().format('Y');
    const isCurrentDayGreater = parseInt(currentDay) > day;

    currentYear = isCurrentDayGreater && parseInt(currentMonth) === 12 ? moment().add(1, 'year').format('Y') : currentYear;
    currentMonth = isCurrentDayGreater ? moment().add(1, 'months').format('M') : currentMonth;

    const salaryDate = moment(`${day}-${currentMonth}-${currentYear}`, 'DD-MM-YYYY');

    return salaryDate.diff(today, 'days');
}

getDaysTillSalary(8);

I'm sure there is a cleaner and maybe efficient way to solve this problem, and will be glad to get some feedback.

Answer 1

const currentDay = moment().format('D');

You use .format() a lot, instead use Moment.js's getters like .date(). This way you also don't have to use parseInt() since the getters return number's.

---

What about this solution:

const getDaysTillSalary = (day) => {
  let date = moment();
  let days = 0;
  while(date.date() !== 8) {
    date = date.add(1, 'day');
    days++;
  }
  return days;
}

It creates a variable and stores the current Moment.js date in it. Then it repeatedly adds one day using .add() and counts up until date.date() (the day of the month) returns 8. The days variable is then returned.