in-seconds

Simply convert days, weeks, months, etc. to seconds.

And that's basically it. Typescript supported.

Also check out in-milliseconds

import inSeconds from "in-seconds";

inSeconds.minutes(2) // 120
inSeconds.hours(2) // 7200
inSeconds.days(5) // 432000
inSeconds.weeks(4) // 2419200
inSeconds.months(11) // 28512000
inSeconds.years(2) // 63072000

Important note

months calculates with 30 days per month. You can change that by passing a number for the daysInMonth argument (it's the second argument).

years calculates with 365 days per year. You can change that by passing a number for the daysInYear argument (it's the second argument).