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:
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Faster than JavaScript
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Has a smaller file size
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Can be compiled to from pretty much any programming language
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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?
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
But other than that, Mrs. Lincoln, how was the play?
You’ve gotten several other answers that are true and correct - the pain of implementation at this point is greater than the pain points that WASM solves. But this is also a non trivial one - most of what Javascript should be doing on a webpage is DOM manipulation.
At some point, WASM will either come out with a killer feature/killer app/use case that Javascript (and all the libraries/frameworks out there) hasn’t figured out how to handle, and it will establish a niche (besides “Javascript is sort of a dumb language let’s get rid of it”), and depending on the use case, you might see some of the 17.4 million (estimated) Javascript developers chuck it for…what? Rust? Kotlin? C? C#? But the switching costs are non-trivial - and frankly, especially if you still have to write Javascript in order to manipulate the DOM…well, what are we solving for?
If you’re writing a web app where one of the WASM languages gives you a real competitive advantage, I’d say that’s your use case right there. But since most web applications are basically strings of api calls looped together to dump data from the backend into a browser, it’s hard to picture wider adoption. I’ve been wrong before, though.
I’d imagine one of those killer features is using a language with a solid standard library. Npm dependencies are notoriously complex because js as a language is missing basic functionality that is standard in other languages. Just a few years ago the Internet broke because “pad left” was pulled by it’s maintainer, that simply doesn’t happen in other languages
From a maintenance perspective npm is a nightmare. From a security perspective it is worse. Being able to build your entire website using a language that eliminates most dependencies, and the ones you take on don’t pull in a zillion dependencies either, is absolutely a killer feature
Of course that isn’t the full story and using js still has it’s advantages as people have already pointed out. If wasm closes the gap in those areas then it would absolutely be worth the switch
Even if WASM gets some amazing feature, like super-fast DOM manipulation, it would still be used via API from JavaScript. WASM is a subset of JavaScript that mainly consists of low level operations. It’s not exactly nice for writing code. It’s like assembler in this respect — very fast, very efficient, but we still tend to prefer a higher level language.
How is WebAssembly a subset of JavaScript? Aren’t you confusing it with asm.js?
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.
What about maintainability of large code bases? JS even with TS tacked isn’t so great or at least not as good as Rust.
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.
Indeed. Who runs into the speed and size limitations of Js itself nowadays? Even freaking Office365, Google apps and observability dashboads run fairly smootly on Js. Not saying there are no legitimate use-cases out there, but I see plenty of reasons for not wanting to fight with the borrow checker if all I am doing is serving up a boring website with some forms and dynamic elements.
There are legitimate use cases out there. And it is not just about speed. Rust is the most loved language for good reason and people wanting to use it in the browser rather than JS because they like is more is as good a use case as any. And this is despite the borrow checker issues - which are really only a problem when you are first learning rust.
These days the rust web frameworks available are very close to the JS frameworks in terms of ergonomics as well as speed. There are even isomorphic web frameworks now that let you write rust code on the backend and frontend using a single rendering code for both. It can be very nice to have both the frontend and backend logic in the same language and even share the same code. And for anyone that does not enjoy JS as a language now has another option to do this with. That IMO is enough of a use case to warrant it.
Though the frameworks are still maturing and have a few rough edges. Plus it is often not worth the effort to port old projects. But new greenfield projects are another matter. But the bigger question for this side is then hiring talent - and ATM JS is easier to hire for, for frontend developers.
Over time this might change, but only very slowly.
Language preference, ergonomics and isomorphic code have not been good enough use-cases to get people off of Js. There was a big hype around compiling to Js a decade ago, but that hype past us and nowadays this is usually only done for some small piece of pure logic that really needs to be isomorphic, which is kind of what we have wasm for nowadays. People who hate Js should really get off their high horse. Writing frontend code in Rust really isn’t going to make a material improvement over writing the same thing in TypeScript, unless you need raw performance which is less than a percent of all webapps.
This is a good thing, because the frontend community is really not going to benefit from having the same thing written in a dozen languages. We’ve already got a bazillion datepickers, we don’t need a gazillion. People are dumb enough to want to rewrite a bunch of stuff in Rust just because they like the language. And Rust absolutely isn’t the best language to write a datepicker in. Having a single language, however crappy, did create some much needed stability in the frontend space. It is also quite handy that frontend engineers can focus on their job, not on learning language X with toolchain Y and libraries Z.
Don’t get me wrong. I am not a Js fan. I’ve been coding since the 90s and am familiar with most languages and pretty much every paradigm. I can be quite picky when it comes to languages, but I’d rather have a single okay language that gets the job done with a good ecosystem then a dozen competing ecosystems some of which may be better in some respects. The current status quo with the advent of TypeScript isn’t terrible either. What is shitty though, is React and the complete lack of use of web standards, but that’s another tangental discussion.
I’ve ported games to web using WASM. You still need to interact with HTML DOM using JS, no way around it.
You use WASM when you either need raw CPU speed, or you have some C++ code that you don’t want to rewrite in JS.
If you just want to make a website, pure JS is better, unless you’re that kind of dev who prefers to render their own text strings pixel by pixel.
Replacing costs expertise, time, and money. Nobody wants to invest that for (to them) insignificant or even pointless reasons.
If you’re using tooling, a framework, a library - each of those makes a switch more risky, costly, or impossible.
JavaScript works with the DOM. Why would you want to implement a separate WASM component that you have to interface with? JavaScript is good enough. Interfacing only brings problems with it.
When you use JS you are doing it right - because there is no other way to interface with the DOM. Anything else is built on top. How would you interface with WASM? Manually? Library? Framework? What programming do you use to compile to WASM with? How do you analyze and debug WASM when it executes in a compiled WASM-binary format?
The use case for WASM is performance, efficiency on CPU-bound operations. If CPU-bound performance is not a concern for you, or JS is good enough, there’s little reason to use WASM. Other reasons are even more niche.
The language best suited for wasm is easily rust. And you can still interface with the Dom using frameworks like yew sycamore or leptos.
Debugging is still a little tricky but you can debug wasm in chrome and DWARF allows you to have source maps that map to your rust code. This is s problem the community is working to improve. Until then you have the full power of console log which is how a large portion of developers already debug their applications.
