I've been wondering about this for a while and haven't really found a great answer for it. From what I understand, WASM is:

  • Faster than JavaScript

  • Has a smaller file size

  • Can be compiled to from pretty much any programming language

  • Can be used outside of the browser easier thanks to WASI

So why aren't most websites starting to try replacing (most) JS with WASM now that it's supported by every major browser? The most compelling argument I heard is that WASM can't manipulate the DOM and a lot of people don't want to deal with gluing JS code to it, but aside from that, is there something I'm missing?

  • nous@programming.dev
    ·
    1 year ago

    Faster than JavaScript

    For pure computation, using the right language it can be faster. For a general website that needs to manipulate the DOM the performance is about the same as what popular JS frameworks can do (and can be faster than popular ones like react). But there are faster JS frameworks that react already available and people are not flocking away from react to these other frameworks. So speed is not a big enough issue here for people to want to move to a new language with WASM.

    Has a smaller file size

    Not sure this is true. Maybe for a single function. But for a general application? I don't think so. WASM tends to be a bit larger than JS code I think as you often need to ship more code, where JS can rely more on things built into the browser. But we are at a point where this difference is not a huge concern any more either. So is not really a point for or against WASM here.

    Can be compiled to from pretty much any programming language

    This is a huge misleading point. Even if you could do it from any language not all languages have a ecosystem that is useable for it and a lot of languages require large runtimes that need to be shipped with the WASM bundle (making the points above far worst).

    Can be used outside of the browser easier thanks to WASI

    So can JS? And native code? So I don't really see what this statement is meant to be arguing for? It is irrelevant when talking about websites using WASM in the browser.

    So why aren’t most websites starting to try replacing (most) JS with WASM now that it’s supported by every major browser?

    Why should they start using it? They all have existing code, their devs already know JS. What major advantage would WASM give them over what they currently have? The points above I have already gone through and are not a big enough reason for this change outside of niche use cases. JS is good enough for most use cases and people that are already working in the web browser side of things already know it. There is little reason to make the switch to WASM as even in languages like rust, which likely has the most mature eco system, still has a vastly less mature eco system for web dev than JS.

    There is no line that needs to be passed that will cause floods of people to start adopting it and start converting everything they maintain over towards it. If there is a good enough reason to adopt this technology then it will be done very gradually over many years if not decades. People wont suddenly throw out everything once some line is crossed without some extreme and unconditional benefit to doing so.

    • jim_stark@programming.dev
      ·
      1 year ago

      What about maintainability of large code bases? JS even with TS tacked isn't so great or at least not as good as Rust.

      • nous@programming.dev
        ·
        1 year ago

        Yes, that is a good reason to use languages like rust overall. And one reason we are seeing quite a few web frontend frameworks being written in rust now. They are maturing quite fast and there is quite a bit of effort being put into them. But i believe most of this is coming from rust devs (that may have touched frontend tech before) wanting to use it in more places rather than JS devs wanting something more maintainable.

        There is quite a lot you can do in languages like JS to help mitigate the maintainability issues as projects scale up in it. TS is one such thing that helps quite a lot and when employed well improves things quite a lot - enough of a difference that it makes the jump to a completely different language and tooling that moving to rust would involve become less attractive. There is still benefit of rust over TS, but also a much bigger cost than switching from JS to TS.

        Some will see the switch as worth it, though more for newer/greenfield projects. Or those coming from backend already written in rust and thus already familiar with the language. Over time these types of projects and situations will grow - but that happens very slowly over time and not just because some line gets crossed by the technology. It also wont cause it to take over everything, but will just get a small market share of everything being written now.

        This is also why we have so many different backend languages rather than one that everyone uses. If one language cannot take over that why would it work for the frontend? At best more websites will start suing other languages over time and slowly erode JSs market share in the web frontend space.