• @miellaby@jlai.lu
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    1712 hours ago

    I’ve seen code in my workplace using parseInt to round JS Number. Made me cringe coming from system programing but I didn’t see the danger.

    It’s sad the only way to prevent such a bad code in production is to use transpilers.

    • @towerful@programming.dev
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      7519 hours ago

      Yup. parseInt is for strings.
      Math.floor, Math.ceil, Math.round or Math.trunc are for numeric type “conversions” (cause its still a float)

      • @mmddmm@lemm.ee
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        18 hours ago

        Nah, it’s stupid either way.

        “5e-7” is not an int to be parsed. Neither is “0.5”.

        • @ThirdConsul@lemmy.ml
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          2 hours ago

          Ah, folly of untyped systems. Tbh this behaviour makes sense given the rules implemented within the language. Anything passed to parseInt is casted to string and then parsed.

          Is it shitty behaviour - yes. Does it make sense in given the language implementation - yes.

        • @LeninOnAPrayer@lemm.ee
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          18 hours ago

          People give JS a lot of shit. And I do too. But it’s meant to continue running and not fail like C code would. It’s meant to basically go “yeah, sure I’ll fuck with that” and keep trucking.

          So you can always make it do stupid shit when you use it a stupid way.

          Is this bad? Maybe. Was it the intention of the language? Absolutely.

          Typescript fixes a lot of these headaches. But I feel like JS is doing exactly what it was meant to do. Keep trucking even when the programmer asks it to do stupid shit.

          If you’re using JS and don’t understand this then it’s your fault and not the languages fault.

          Do we all want to live in a world of typedefs as strict as C and have our webpages crash with the slightest unexpected char input? Probably not.

          We don’t notice all the time JS goes “yeah I can fuck with that” and it works perfectly. We only notice the times it does that and it results in something silly.

          TLDR: JS does what it was made to do. And because of that it looks absolutely ridiculous sometimes.

          • @JakenVeina@lemm.ee
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            76 hours ago

            The REAL problem is that the industry collectively uses JS almost exclusively for shit it was never meant to do. Like you say, it’s intended for it to not throw errors and kill your whole web page, because it was only ever intended to be used for minor scripts inside mostly-static HTML and CSS web pages. Then we all turned it into the most-popular language in the world for building GUI applications.

          • @mmddmm@lemm.ee
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            812 hours ago

            It’s meant to basically go “yeah, sure I’ll fuck with that” and keep trucking.

            Yet, it lives in an insulated environment, with plenty of infrastructure to make sure errors do not propagate, with a standard error handling functionality on the spotlight with specialized syntax, and with plenty of situations where it just drops the ball and throws an error.

            Nope, not falling for the gaslight. It’s a stupid feature that’s there because the language was created during a week and the author was trying to juggle the requirement of a rigid and typed semantics that looked like Java with his desire to make a flexible single-typed language that looks like Lisp.

            And nobody fixed it, decades later, because everybody keeps repeating your line that the interpreter must always keep on.

          • @leftytighty@slrpnk.net
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            3717 hours ago

            People forget that crashes are a debugging tool indicating an error. Silent errors can be much more dangerous. C and C++ in particular need to be careful not to overwrite random memory for example.

            Yes the consequences for JS failures are less severe and so JS can get away with it, but a crash is a way to know your program isn’t doing what you thought it was, properly.

            It just so happens that JS is used in contexts where nobody really cares, and errors aren’t a big deal, cheap and fast wins.

          • @Blackmist@feddit.uk
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            512 hours ago

            My main issue with JS is you can use it wrong, and it pretends to work, and often looks like it works.

            But then shits its pants explosively the second you fall outside that.

          • @wischi@programming.dev
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            317 hours ago

            That’s not why JS is a big pile of crap. It’s because the language was not thought through at the beginning (I don’t blame the inventors for that) and because of the web it spread like wildfire and only backwards compatible changes could be made. Even if will all your points in mind the language could be way nicer. My guess is that once wasm/wasi is integrated enough to run websites without JS (dom access, etc.) JS will be like Fortran, Cobol and Telefax - not going away any time soon, but practically obsolete.

    • @FiskFisk33@startrek.website
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      25 hours ago

      oh god the reason is even stupider then I expected

      Because large numbers use the e character in their string representation (e.g., 6.022e23 for 6.022 × 1023), using parseInt to truncate numbers will produce unexpected results when used on very large or very small numbers. parseInt should not be used as a substitute for Math.trunc().

    • @tauonite@lemmy.world
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      11 hours ago

      Holy fuck that is long. When the documentation for the integer parsing function is 10 pages long, there’s something seriously wrong with the language

      • Lemminary
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        611 hours ago

        Is it? I’ve seen longer articles for C# and not as many complaints about it.

        • @barsoap@lemm.ee
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          59 hours ago

          Probably not an article about integer parsing, though. If the docs are that long, then because Microsoft does have a tendency to be overly verbose for things they think you need, just to have no docs for the stuff you actually need.

          For reference here’s the relevant rust docs.

    • @barsoap@lemm.ee
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      12 hours ago

      https://en.wikipedia.org/wiki/Principle_of_least_astonishment

      …and of course JS made it into the examples, how could it not:

      A programming language’s standard library usually provides a function similar to the pseudocode ParseInteger(string, radix), which creates a machine-readable integer from a string of human-readable digits. The radix conventionally defaults to 10, meaning the string is interpreted as decimal (base 10). This function usually supports other bases, like binary (base 2) and octal (base 8), but only when they are specified explicitly. In a departure from this convention, JavaScript originally defaulted to base 8 for strings beginning with “0”, causing developer confusion and software bugs. This was discouraged in ECMAScript 3 and dropped in ECMAScript 5.

    • @jsomae@lemmy.ml
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      12 hours ago

      Okay but this documentation is obviously wrong from the first sentence

      The parseInt() function parses a string argument and returns an integer of the specified radix

      Integers don’t have radices. It should read:

      The parseInt() function parses a string argument representing an integer of the specified radix and returns that integer.

      Either way, I still don’t understand the behaviour in the image. nvm, thanks m_f@discuss.online

    • @Zacryon@feddit.org
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      917 hours ago

      I’d advise to always look into the corresponding documentation before using something from any library.

      • @pinball_wizard@lemmy.zip
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        411 hours ago

        But I’m too busy being confused by the behaviors of libraries I previously didn’t read the documentation for, to read the documentation for every new library I adopt.

        (This is sarcasm…mostly.)

  • @danda@lemmy.zip
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    9821 hours ago

    It’s because parseInt is expecting a string, so the decimal gets converted to a string, and 0.0000005.toString() returns 5e-7.

    • Victor
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      319 hours ago

      Classic people who don’t know how to code wat. Passing a number in place of a string argument because they don’t know what they’re doing.

      • @jjjalljs@ttrpg.network
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        3419 hours ago

        Javascript could throw an error to alert you that the input is supposed to be a string, like most languages would do.

        • Victor
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          15 hours ago

          But you’re calling a function specifically made for passing a string to an int… 😆 There’s gotta be some common sense somewhere here, guys.

          Still, it’s a very good point. JS should do this.

          I would suspect one reason it doesn’t do this is to be backwards compatible.

          • @listless
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            27 hours ago

            And god fucking forbid that common sense be in the language. Who the fuck needs a language with common sense, amirite?

        • @heavy@sh.itjust.works
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          -318 hours ago

          Theoretically, Javascript is an untyped language, so there aren’t supposed to really be static types. Giving type errors in this situation would be against design.

      • Traister101
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        2219 hours ago

        It’s not a string argument though, it’s JS. You can argue it’s expected to be a string but like the rest of JS all you can know from the signature alone is that it takes an object. Hopefully your little ducky quacks the right way!

        • Victor
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          -116 hours ago

          It’s not a string argument though, it’s JS

          Huh? The code in the image is passing a number argument where there should be a string argument.

          And this function is specifically made to parse a string into an int. Apply common sense.

          • Traister101
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            -114 hours ago

            JavaScript doesn’t have typed parameters or variables. The function expects a string and does things in the function body which converts the object into a string. JS shares this behavior with all dynamically typed languages and it’s extremely useful in some contexts and extremely frustrating in others. It’s down to what it’s being used for. Dynamic languages make excellent scripting languages, see Python really just being a souped up shell lang

            • Victor
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              5 hours ago

              The function expects a string and does things in the function body which converts the object into a string.

              … These are different words that describe exactly what I’m saying. I’m saying: in the place where there should be a string argument, because the function expects one, there is not a string argument, but a number argument. (Not an object like you keep saying.)

              I know all that stuff about dynamically typed languages. I’m just saying that the function is being used incorrectly here.

              • Traister101
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                012 hours ago

                You cannot have a string argument, arguments and variables in JS don’t have a type. All you have in JS is objects. Actual functions, like full on function foo(){} are still objects, like you can actually store data on the things.

                • Victor
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                  5 hours ago

                  I think you confuse argument with parameter. You cannot specify the type of the parameter, but any argument you supply to a function in JS has a type. Every value in JS has a type, arguments included.

                  If I go:

                  const n = 0.0000005;
                  console.log(typeof n);
                  

                  The code above will print “number”. And you cannot assign n.foo = "metadata"; to this value of a primitive type. Not everything is an object.

                  Either way, arguments have types, values have types. The arguments in this case were of type “number”, when they should have been “string”.

      • @qqq@lemmy.world
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        19 hours ago

        Could be a variable from somewhere else in the code. It should throw type error of some sort if it’s not going to handle a float correctly

        • Victor
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          115 hours ago

          Agreed, functions in general should do this, and some do. But it should probably be automatic. And the variable argument is a good one, a very good argument for TypeScript. ❤️