Luxon Manual Reference


Invalid DateTimes

One of the most irritating aspects of programming with time is that it's possible to end up with invalid dates. This is a bit subtle: barring integer overflows, there's no count of milliseconds that don't correspond to a valid DateTime, but when working with calendar units, it's pretty easy to say something like "June 400th". Luxon considers that invalid and will mark it accordingly.

Unless you've asked Luxon to throw an exception when it creates an invalid DateTime (see more on that below), it will fail silently, creating an instance that doesn't know how to do anything. You can check validity with isValid:

> var dt = DateTime.fromObject({ month: 6, day: 400 });
dt.isValid //=> false

All of the methods or getters that return primitives return degenerate ones:

dt.year; //=>  NaN
dt.toString(); //=> 'Invalid DateTime'
dt.toObject(); //=> {}

Methods that return other Luxon objects will return invalid ones:{ days: 4 }).isValid; //=> false

Reasons a DateTimes can be invalid

The most common way to do that is to over- or underflow some unit:

But there are other ways to do it:

// specify a time zone that doesn't exist"America/Blorp").isValid; //=> false

// provide contradictory information (here, this date is not a Wednesday)
DateTime.fromObject({ year: 2017, month: 5, day: 25, weekday: 3 }).isValid; //=> false

Note that some other kinds of mistakes throw, based on our judgment that they are more likely programmer errors than data issues:{ blorp: 7 }); //=> kerplosion

Debugging invalid DateTimes

Because DateTimes fail silently, they can be a pain to debug. Luxon has some features that can help.

invalidReason and invalidExplanation

Invalid DateTime objects are happy to tell you why they're invalid. invalidReason will give you a consistent error code you can use, whereas invalidExplanation will spell it out

var dt ="America/Blorp");
dt.invalidReason; //=>  'unsupported zone'
dt.invalidExplanation; //=> 'the zone "America/Blorp" is not supported'


You can make Luxon throw whenever it creates an invalid DateTime. The message will combine invalidReason and invalidExplanation:

Settings.throwOnInvalid = true;"America/Blorp"); //=> Error: Invalid DateTime: unsupported zone: the zone "America/Blorp" is not supported

You can of course leave this on in production too, but be sure to try/catch it appropriately.

Invalid Durations

Durations can be invalid too. The easiest way to get one is to diff an invalid DateTime.

DateTime.local(2017, 28).diffNow().isValid; //=> false

Invalid Intervals

Intervals can be invalid. This can happen a few different ways: