luxon plus

JavaScript
DateTime.local().plus(123) //~> in 123 milliseconds
DateTime.local().plus({ minutes: 15 }) //~> in 15 minutes
DateTime.local().plus({ days: 1 }) //~> this time tomorrow
DateTime.local().plus({ days: -1 }) //~> this time yesterday
DateTime.local().plus({ hours: 3, minutes: 13 }) //~> in 3 hr, 13 min
DateTime.local().plus(Duration.fromObject({ hours: 3, minutes: 13 })) //~> in 3 hr, 13 min
Source

Also in JavaScript: