• Julian@lemm.ee
    241·
    2 years ago

    Ok some of these I understand but what the fuck. Why.

    Edit: ok I have a theory. == checks equality without casting to any types, so they’re not equal. But < and > are numeric operations, so null gets cast to 0. So <= and >= cast it to 0, and it’s equal to 0, so it’s true.

    • RagingToad@feddit.nl
      151·
      2 years ago

      I’m not sure if you really want to know, but:

      greater than, smaller than, will cast the type so it will be 0>0 which is false, ofcourse. 0>=0 is true.

      Now == will first compare types, they are different types so it’s false.

      Also I’m a JavaScript Dev and if I ever see someone I work with use these kind of hacks I’m never working together with them again unless they apologize a lot and wash their dirty typing hands with… acid? :-)

      edit: as several people already pointed out, my answer is not accurate. The real solution was mentioned by mycus

      • hstde@lemmy.fmhy.ml
        2·
        2 years ago

        Not a JavaScript dev here, but I work with it. Doesn’t “==” do type coercion, though? Isn’t that why “===” exists?

        As far as I know the operators “>=” and “<=” are implemented as the negation of “<” and “>” respectively. Why: because when you are working with sticky ordered sets, like natural numbers, those operators work.

        Thus “0<=0” -> “!(0>0)” -> “!(false)” -> “true”

        Correct me if my thinking is wrong though.

  • Mars@beehaw.org
    122·
    2 years ago

    I know it’s a joke, but it’s an old one and it doesn’t make a lot of sense in this day and age.

    Why are you comparing null to numbers? Shouldn’t you be assuring your values are valid first? Why are you using the “cast everything to the type you see fit and compare” operator?

    Other languages would simply fail. Once more JavaScript greatest sin is not throwing an exception when you ask it to do things that don’t make sense.

    • OsrsNeedsF2POP
      6·
      2 years ago

      Shouldn’t you be assuring your values are valid first?

      Step 1: Get to prod

      Step 2-10: Add features

      Step 11: Sell the company before it bites you

      • Mars@beehaw.org
        2·
        2 years ago

        As a professional bite-mean-for-other-guy taker (right now in Java) this hurts my feelings.

  • PlexSheep@feddit.de
    4·
    2 years ago

    I wrote an exam about this stuff yesterday.

    In J’s equality is usually checked in a way that variables are casted to the type of the other one. “25” == 25 evaluates to truey because the string converted to int is equal to the int and the other way around.

    You can however check if the thing is identical, using “25” == 25 which skips type conversion and would evaluate as false.

    I assume the same thing happens here, null is casted to int, which gets the value 0.

  • sheetmulch@kbin.social
    4·
    2 years ago

    I had a fun bug where unit tests started failing on an upgrade. Turns out someone was returning undefined from a comparator. Wtf, people.

  • Björn Tantau@feddit.de
    1·
    2 years ago

    Can someone explain this? I mean, the last result. Usually I can at least understand Javascript’s or PHP’s quirks. But this time I’m stumped.