How to calculate a duration between two dates in luxon?

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Luxon's documentation for the Duration.fromISO method describes it as

Create a Duration from an ISO 8601 duration string

Nowhere is mentioned the ability to create a duration based on two dates. My typical use case would be: "did the event between date ISODAT1 and ISODATE2 last more than an hour?".

What I will do is to transform the dates into a timestamp and check whether the difference is greater than 3600 (seconds), I believe however that there is a more native way to make the check.

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2 Answers

You could use DateTime's .diff (doc)

Return the difference between two DateTimes as a Duration.

const date1 = luxon.DateTime.fromISO("2020-09-06T12:00")
const date2 = luxon.DateTime.fromISO("2019-06-10T14:00")

const diff = date1.diff(date2, ["years", "months", "days", "hours"])

console.log(diff.toObject())
<script src="https://cdn.jsdelivr.net/npm/luxon@1.25.0/build/global/luxon.min.js"></script>

user_66551600

Example

const date1 = luxon.DateTime.fromISO("2020-09-06T12:00");
const date2 = luxon.DateTime.fromISO("2019-06-10T14:00");
const diff = Interval.fromDateTimes(later, now);
const diffHours = diff.length('hours');

if (diffHours > 1) {
  // ...
}

Documentation for Luxon v2.x

In the Luxon documentation they mention durations and intervals. It seems that you would be best off using Intervals and then calling the .length('hours') on the Interval if you're interested to know if something has been over an hour.

Durations

The Duration class represents a quantity of time such as "2 hours and 7 minutes".

const dur = Duration.fromObject({ hours: 2, minutes: 7 });

dur.hours;   //=> 2
dur.minutes; //=> 7
dur.seconds; //=> 0

dur.as('seconds'); //=> 7620
dur.toObject();    //=> { hours: 2, minutes: 7 }
dur.toISO();       //=> 'PT2H7M'

Intervals

Intervals are a specific period of time, such as "between now and midnight". They're really a wrapper for two DateTimes that form its endpoints.

const now = DateTime.now();
const later = DateTime.local(2020, 10, 12);
const i = Interval.fromDateTimes(now, later);

i.length()                             //=> 97098768468
i.length('years')                      //=> 3.0762420239726027
i.contains(DateTime.local(2019))       //=> true

i.toISO()       //=> '2017-09-14T04:07:11.532-04:00/2020-10-12T00:00:00.000-04:00'
i.toString()    //=> '[2017-09-14T04:07:11.532-04:00 – 2020-10-12T00:00:00.000-04:00)
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