getSecondsDiffBetweenDates Calculates the difference (in seconds) between two dates. Subtract the two Date objects and divide by the number of milliseconds in a second to get the difference (in seconds) between them. const getSecondsDiffBetweenDates = (dateInitial, dateFinal) => (dateFinal - dateInitial) / 1000; getSecondsDiffBetweenDates( new Date('2020-12-24 00:00:15'), new Date('2020-12-24 00:00:17') ); // 2