If you run this JavaScript function on the 31st of a month, the result will be a month off. The best part is that this is the intended behvaior. JavaScript is a cursed language. (lemmy.ml)

submitted 10 months ago by yogthos@lemmy.ml to c/programmerhumor@lemmy.ml

47 comments fedilink hide all child comments

function getMonthName(monthNumber) {
  const date = new Date();
  date.setMonth(monthNumber - 1);

  return date.toLocaleString([], { month: 'long' });
}

The current day of month will have an impact on the behavior of this method. Conceptually it will add the number of days given by the current day of the month to the 1st day of the new month specified as the parameter, to return the new date. For example, if the current value is 31st January 2016, calling setMonth with a value of 1 will return 2nd March 2016. This is because in 2016 February had 29 days.

you are viewing a single comment's thread
view the rest of the comments

[-] yogthos@lemmygrad.ml 3 points 10 months ago

This is literally how every sane API works in languages built by adults. For example, here's what happens in Java:

java.time.LocalDate.of(2023, 3, 31)
> #object[java.time.LocalDate 0x2bc77260 "2023-03-31"]
java.time.LocalDate.of(2023, 3, 31).minusMonths(1)
> #object[java.time.LocalDate 0xac0dc15 "2023-02-28"]
java.time.LocalDate.of(2023, 3, 31).minusMonths(2)
> #object[java.time.LocalDate 0x44b9305f "2023-01-31"]

I have no idea where people get this notion that a month isn't a defined size. Do people just not understand the concept of a month?

this post was submitted on 06 Nov 2023

31 points (69.1% liked)

Programmer Humor

32060 readers

2643 users here now

Post funny things about programming here! (Or just rant about your favourite programming language.)

Rules:

Posts must be relevant to programming, programmers, or computer science.
No NSFW content.
Jokes must be in good taste. No hate speech, bigotry, etc.

founded 5 years ago

MODERATORS

AgreeableLandscape@lemmy.ml

cat_programmer@lemmy.ml