$ npm i -g google-apps-script
$ gas new myProject && cd myProject
$ gas i -s time
$ gas push
Number of complete days between two dates
time_dayDiff(StartDate, EndDate);
Number of complete hours between two dates
time_hourDiff(StartDate, EndDate);
Number of complete minutes between two dates
time_minuteDiff(StartDate, EndDate);
Number of complete seconds between two dates
time_secondDiff(StartDate, EndDate);