How to calculate date difference in JavaScript?

Question

I want to calculate date difference in days, hours, minutes, seconds, milliseconds, nanoseconds. How can I do it?

Answer 1

Ok, there are a bunch of ways you can do that. Yes, you can use plain old JS. Just try:

let dt1 = new Date()
let dt2 = new Date()

Let's emulate passage using Date.prototype.setMinutes and make sure we are in range.

dt1.setMinutes(7)
dt2.setMinutes(42)
console.log('Elapsed seconds:',(dt2-dt1)/1000)

Alternatively you could use some library like js-joda, where you can easily do things like this (directly from docs):

var dt1 = LocalDateTime.parse("2016-02-26T23:55:42.123");
var dt2 = dt1
  .plusYears(6)
  .plusMonths(12)
  .plusHours(2)
  .plusMinutes(42)
  .plusSeconds(12);

// obtain the duration between the two dates
dt1.until(dt2, ChronoUnit.YEARS); // 7
dt1.until(dt2, ChronoUnit.MONTHS); // 84
dt1.until(dt2, ChronoUnit.WEEKS); // 356
dt1.until(dt2, ChronoUnit.DAYS); // 2557
dt1.until(dt2, ChronoUnit.HOURS); // 61370
dt1.until(dt2, ChronoUnit.MINUTES); // 3682242
dt1.until(dt2, ChronoUnit.SECONDS); // 220934532

There are plenty more libraries ofc, but js-joda has an added bonus of being available also in Java, where it has been extensively tested. All those tests have been migrated to js-joda, it's also immutable.