compare only dates with luxon Datetime

Question

I have two luxon objects,

let startDate = DateTime.fromISO(startDate)
let someDate = DateTime.fromISO(someDate)

How can I compare if someDate is <= startDate, only the dates, without the time?

Vandal

Do you have issue using < and >? From luxon Comparing DateTimes section of the manual: DateTime implements #valueOf to return the epoch timestamp, so you can compare DateTimes with <, >, <=, and >=. That lets you find out if one DateTime is after or before another DateTime. – Norikonorina

Sorry, I have updated my question – Vandal

Which are the values of startDate and someDate? Maybe you can use startOf, but I think that no matter the time, if a date is previous another one you will get the right result using <, >, <= and >= – Norikonorina

Answer 1

To compare just the dates, use startOf

startDate.startOf("day") <= someDate.startOf("day")

Hahnke

we can also check equality by using timestamp startDate.startOf('day').ts == someDate.startOf("day").ts – Ashcan

I think that if you want to check equality it is better to do something like this: startDate.hasSame(someDate, "day") – Evora

Answer 2

Documentation: https://moment.github.io/luxon/#/math?id=comparing-datetimes

var DateTime = luxon.DateTime;

var d1 = DateTime.fromISO('2017-04-30');
var d2 = DateTime.fromISO('2017-04-01');

console.log(d2 < d1); //=> true
console.log(d2 > d1); //=> false

<script src="https://moment.github.io/luxon/global/luxon.min.js"></script>

Shortsighted

This does not address comparison of only Date components of the DateTime objects. The example in this answer will still compare time components if they are present. – Reggiereggis

@MarkClark that is why we use luxon instead – Shortsighted

I'm not talking about JS dates; DateTime is luxon. I don't understand what you are getting at. – Reggiereggis

@MarkClark I guess I did not know DateTime has a Date component. I thought you were referring to a JavaScript Date. – Shortsighted

It doesn't. I am referring to "date component" as a concept. Luxon's DateTime is three concepts rolled into one object, date, time, and timezone. When using comparison operators (>,<,=), it will compare those objects with respect to all three concepts, irrelevant of how they were initialized (as in your example with only date strings). The original question explicitly asks about comparing only the date concept of two arbitrary luxon DateTimes. Hence my initial protest to this answer. – Reggiereggis

This did the job thanks @Shortsighted – Acre

Answer 3

As an additional option, if your input strings are known to be ISO 8601 strings as hinted in your question, it's valid to compare them lexicographically:

"2007-01-17T08:00:00Z" < "2008-01-17T08:00:00Z" === true;
"2007-01-17" < "2008-01-17" === true;

Lassalle

Answer 4

Another option presented by this github issue could be to create your own Date class:

Luxon doesn’t have any support for [separate Date classes] but it’s easy to do through composition: create a Date class that wraps DateTime and exposes the subset of methods you need. You can decide how pure of abstraction you need to provide to your application (ie how much work you want to do to make your wrapper full featured and pure)

Haberman

Answer 5

Use ordinal to get the day of the year as an integer, see https://moment.github.io/luxon/docs/class/src/datetime.js~DateTime.html#instance-get-ordinal

startDate.ordinal <= someDate.ordinal

Note

The accepted answer did not work for me, but this did. Thanks! – Hoashis

This is a somewhat dangerous answer; if the startDate is a different year than someDate, all bets are off. It will think than Jan 1, 2021 is before Dec 31, 2020, for example. – Hahnke

Answer 6

Neither of these answers work with leap years. I found success with the following,

function dateTimesAreSameDay(dateTime1, dateTime2) {
  return dateTime1.year === dateTime2.year && dateTime1.month === dateTime2.month && dateTime1.day === dateTime2.day;
}

Hyperbole

What about January 1st in different years? – Drawknife

Great point! Updated to take this into account, not sure how I missed that one. – Hyperbole