• QuazarOmega@lemy.lol
      link
      fedilink
      arrow-up
      0
      ·
      10 months ago
      > 1 == 1
      true
      > 1 == '1'
      true
      > 1 === '1'
      false
      

      (from node REPL)

      Basically it’s the real equals sign perfection

    • kevincox@lemmy.ml
      link
      fedilink
      arrow-up
      0
      ·
      10 months ago

      JS’s == has some gotchas and you almost never want to use it. So === is what == should have been.

      All examples are true:

      "1" == true
      [1, 2] == "1,2" 
      " " == false
      null == undefined 
      

      It isn’t that insane. But some invariants that you may expect don’t hold.

      "" == 0
      "0" == 0
      "" != "0" 
      
    • BougieBirdie@lemmy.blahaj.zone
      link
      fedilink
      English
      arrow-up
      0
      ·
      10 months ago

      The other comments explains it in pretty good detail, but when I was learning my teacher explained it sort of like a mnemonic.

      1 + 1 = 2 is read “one plus one equals two”

      1 + 1 == 2 is read “one plus one is equal to two”

      1 + 1 === 2 is read “one plus one is really equal to two”

      And you hit the nail on the head, is that === is type explicit while == is implicit.

      • bobbykjack@programming.dev
        link
        fedilink
        arrow-up
        0
        ·
        edit-2
        10 months ago

        I’d use something like:

        = becomes

        == equals

        === is identical to

        It’s funny how everyone thinks “equals” in this context should be “identical to” when, in normal language, it doesn’t really mean that at all!

    • frezik@midwest.social
      link
      fedilink
      arrow-up
      0
      ·
      10 months ago

      The short answer is that your language needs === when it fucked up the semantics of ==, but it’s also too popular and you can’t fix it without breaking half the web.

    • Mikina@programming.dev
      link
      fedilink
      arrow-up
      0
      ·
      edit-2
      10 months ago

      It’s also important if you’re checking hashes (at least, it was - if you’re using correct hashing algorithm that isn’t ancient, you will not have this problem).

      Because if you take for example “0e462097431906509019562988736854” (which is md5(“240610708”), but also applicable to most other hashing algorithms that hash to a hex string), if(“0e462097431906509019562988736854” == 0) is true. So any other data that hashes to any variantion of “0e[1-9]+” will pass the check, for example:

      md5("240610708") == md5("hashcatqlffzszeRcrt")

      that equals to

      "0e462097431906509019562988736854" == "0e242700999142460696437005736231"

      which thanks to scientific notation and no strict type checking can also mean

      0462097431906509019562988736854 == 0242700999142460696437005736231

      which is

      0 == 0 `

      I did use md5 as an example because the strings are pretty short, but it’s applicable to a whole lot of other hashes. And the problem is that if you use one of the strings that hash to a magic hash in a vulnerable site, it will pass the password check for any user who’s password also hashes to a magic hash. There’s not really a high chance of that happening, but there’s still a lot of hashes that do hash to it.

    • SzethFriendOfNimi@lemmy.world
      link
      fedilink
      arrow-up
      0
      ·
      edit-2
      10 months ago

      So in JavaScript there’s the assignment

      =
      

      and the comparator is

      ==
      

      Since there’s no types JS will do implicit conversion before comparison when using == in a case like this

      if(false == '0'){
          //this is true
      }
      

      But with === it doesn’t. It means literally compare these

      if(false === '0'){
          //this is false
      }else{
          //so this will execute instead 
      }
      

      But this, however, will

      var someState = false;
       if(someState === false){
          //this is true
      }