Date difference in months

Calculates the difference (in months) between two dates.

Use Date.prototype.getFullYear() and Date.prototype.getMonth() to calculate the difference (in months) between two Date objects.

const getMonthsDiffBetweenDates = (dateInitial, dateFinal) =>
  Math.max(
    (dateFinal.getFullYear() - dateInitial.getFullYear()) * 12 +
      dateFinal.getMonth() -
      dateInitial.getMonth(),
    0
  );

// EXAMPLE
getMonthsDiffBetweenDates(new Date('2017-12-13'), new Date('2018-04-29')); // 4

Source

https://www.30secondsofcode.org/js/s/get-months-diff-between-dates