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Programmer Humor @lemmy.ml

tfm @europe.pub

2w ago

JavaScript is awesome

new Date("wtf")

cross-posted from: https://programming.dev/post/33754840

new Date("wtf")

Programmer Humor @programming.dev

Gsus4 @mander.xyz

2w ago

new Date("wtf")

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2w ago

New Date("WTF") – How well do you know JavaScript's Date class?

Programming @programming.dev

Sheldan @programming.dev

2w ago

new Date("wtf")

25 comments

Best laugh I've had in a while. That is some grade-A jank.
- Have you seen https://www.destroyallsoftware.com/talks/wat
  
  I have now, that's fantastic!
  
  Classic
This quiz was stressful. Like, there were so many times when I knew I was being cued up for a trick question, but I still fell for it.
- It's a mess. Expectation is always wrong, basically.
In the process of being replaced.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal
JavaScript has had the Date object for handling date and time since its first days. However, the Date API is based on the poorly designed java.util.Date class from Java, which was replaced in the early 2010s; but, because of JavaScript's goal of backward compatibility, Date sticks around in the language.
- Damn, I thought you meant JavaScript itself was being replaced.
  
  One can only undefined
- Hmm, I can believe that it was based on java.util.Date, but I don't remember that being as unpredictable. I guess, a different API to begin with, would have avoided a lot of problems, though...
It is awesome, in the same way a planet killer asteroid heading straight for us is awesome!
You do not, under any circumstances, "gotta hand it to javascript".
Love this quiz btw
Ah, JavaScript...
Luckily the new Temporal API is shaping up.
- I quite like this one.
Ok, I get that the Date API is problematic, but I wouldn't expect anything meaningfull from new Date("not a date").getTime() anyway. Why would you in the first place?
- Parsing user input? Nonsense data coming from an API?
  
  If you’re expecting shit data then you’d have unit tests for those cases so you’d know what to expect.
- It's mainly horrid, because it means you have to code extremely defensively (or I guess, use a different API).
  You can't rely on new Date("not a date") aborting execution of your function by throwing an error. Instead, you have to know that it can produce an Invalid Date object and check for that. Otherwise a random NaN shows up during execution, which is gonna be extremely fun to try to find the source of.
  I understand that it's implemented like that partially for historical reasons, partially because it's often better to display "NaN" rather than nothing, but it's still the sort of behavior that puts me in a cold sweat, because I should be memorizing all kinds of Best Practices™ before trying to code JavaScript.
- You think you'd get an error from the constructor.
- Because reasonable APIs have input validation provided out of the box, so that not everybody has to reinvent the validation wheel (inevitably incorrectly).
- Because this is a simplified example? Maybe you create the object in one place (saying something more realistic like "2015" or whatever your inexperience or AI told you to) and use getTime() at a later place where you thought you created it in a correct way.
  
  (saying something more realistic like “2015” or whatever your inexperience or AI told you to)
  User input is probably the big one where this API is gonna get stress-tested...
Until the new Temporal API comes along, there are some libraries we can use.
luxon
dayjs
or compile chrono (Rust) to WebAssembly

25 comments