Reactivity
Svelte has cool and simple reactive model. Really easy to understand and use, when I read docs for the first time I had thought why is that wasn’t done before? However, I think there is could be more. I would like svelte to be more reactive, something like array.push could trigger render. As well as methods in custom classes, which mutate this. Probably, it’s possible to check in compile time is method mutate this or not and behavior corresponding.
Async
Asynchronous blocks look fantastic. There is even no need to have an async function in components - just pass promise as props, and Svelte will do everything that should be done. Also, I like how easy to handle exceptions and loading states. However, it's a bit unclear, at least right now, how is it possible to do some logic in case a promise fails? What if you need to repeat a request or make something else?
Template syntax
Do not like template syntax. Reminds some old times with template engines. It doesn’t look modern and elegant. Not really a downside, rather personal aesthetic preference
Event handling
Not sure about putting event modifiers into an event handler assignment. As long as we can write on JavaScript in a handler function body, we can call modifiers against event objects. Looks too much. I think a good solution should try to do as least as possible in general, and personally can't see how that feature makes code easier to read and write.
Custom events
Keeping consistent custom events names could be an annoying and bug-prone task when some wrapper could just propagate the event above in a tree. Maybe it's not a bad idea to make Svelte push developers declare an event name somewhere in a code and import it to the subscription's place
Media
Updating time for video and audio happens in requestAnimationFrame. Why don't in requestIdleCallback?
Lifecycle
Lifecycle functions remind me of old good react (before hooks era), but there is something good from hooks. For instance, the onMount callback could return a function invoked while destroying. It's really convenient, especially while we have the onDestroy lifecycle function. Also, it's excellent that Svelte allows unbound lifecycle functions with components and lets us reuse them just like React hooks! So in comparison to React, these lifecycle functions got the best parts from hooks and lifecycle class methods and did it better, in my opinion.
Layout
Tick - elegant solution, like it a lot. Easy concept, unlike useLayoutEffect. Just great.
Stores
Like everything else in Svelte, stores feel simple to use and understand. API has no complex concept; just subscribe if you wanna data! I have to admit, when I started reading the Svelte tutorial, I was preparing to understand a new complex framework with complex abstractions, etc. But instead, I see one of the best tutorials I’ve ever seen, simple, kind API (I don’t know, I feel that way), syntax, and it’s excellent! It’s like a breath of fresh air in the modern web (sorry, but especially after React hooks).
Transitions
Transitions are funky, but it looks like those features aim to substitute some CSS. To be honest, I have an undefined opinion about that. There is such a high abstraction, so it's easy to make something, but what is the price? Obviously, not performance - everything happens in compile time. Probably skill? It's incredibly newbie-friendly, in my opinion, but it is crucial to keep learning js and DOM fundamentals for beginners. There is a lot of magic under the hood; hence, it's fun and easy to make the frontend with Svelte, but it will end immediately when you need to write some code outside the framework.
Conclusion
Svelte made many common frontends development patterns less boilerplate and less annoying but left expressiveness and even added fun. Frankly, I'm a bit scared about how much framework is doing for me, like I lost control, but that fear isn't rational and shouldn't be considered as a reason to not use Svelte. Actually, the most important conclusion is that - Svelte made me want to write some frontend again 🙂
Photo by Jonny Gios
Top comments (19)
My experience with svelte has been very positive as long as the complexity was low; stuff that would be just as easy with vanilla JS and a fair bit beyond that. But once you get to the really complicated things many of svelte's abstractions become ugly and one starts to use lots of dollar-expressions with countless variables.
I also really dislike the way templating works. This is mostly a matter of taste, but the way certain expressions are a weird mix of JS and HTML syntax (
{#if}being closed with{/if}for example) just seems confusing to me.In fact, I haven't written any Svelte code and wrote those notes while reading the tutorial. And while I was reading, I had similar thoughts about complex apps on Svelte. Are there some good approaches or solutions for dealing with complexity?
Totally agree!
requestIdleCallbackis an experimental API and is not supported in Safari.requestAnimationFrameis the correct function to use anyway - the data of playback position is typically a part of the UI, and it's both important that it's up to date and unnecessary to update many times per frame.Good points, thanks for explanation!
Svelte was a great experience to em for i could straight away starti writing HTMl instead of first writing a function and then exporting it (in React). I don't know why but this very small advantage is a hugeeee one for me. Also, some things like
bind:valueis a huge advantage. I didn often have to do some digging to find compatible libraries but I usually found one and vanilla js libraries usually work the way they should. I would raelly recommend Svelte to anyone making a simple website, trust me, you don't need React for a portfolio site.It has been done before. RiotJS is very similar and has been around considerably longer
The main difference is that Riot relies on
Web Componentsa Web Component like API, while Svelte doesn't. The creator of Svelte has an article here in DEV about why he doesn't like Web Components. Svelte has an option to compile its components as Web Components, but TBH I don't know much people that does that (even more so now with the surge in "transitional apps", aka apps that have the best of SSR and SPA).A few of those reasons are a bit far-fetched though. Like complaining that web components will have to define countless getters for HTML attributes; you can easily just fix that with a bit of meta-programming.
Some things mentioned in that post might haven't aged well, but the thing is that the author of Svelte is not "pro Web Components". Still if you use the API that comes with the browser, you need to use that awkward
attributeChangedCallbackmethod, and if we use an util on top of that or we just don't use it and create a custom approach, then we end up just saying that he's right and using libraries or frameworks is better than using the platform directly X_X .... I just wish at some point we get Web Components 2.0 and the API is better than the one we got for 1.0 😅I kind of disagree though. Using a small abstraction layer to make custom elements more comfortable is still vastly different from using a complete framework that doesn't even use custom elements at all.
What's more, this often isn't even necessary for very simple components: the low-level APIs are often more than enough for those. And as they get more complex, you can first start using meta-programming directly inside the code of your component before moving to a microframework once even that becomes hard to handle, at which point you're probably already building a considerably big component.
As for web components 2.0, I think that's exactly where frameworks should come in. Whether you prefer a huge framework with thousands of lines of code or a small micro-framework like what I use, it's easy to make the current APIs much nicer to use at some performance cost by generating getters/setters or by looking up functions at runtime. The point is that the API leaves the decision to you whether you want to make those trade-offs.
To my knowledge - unless it has changed - Riot doesn't rely on web components either. It does have the option to compile to web components though
You're right, my bad, it has a "Web component like API". Based on the syntax and the actual Riot site, I thought they were generating Web Components using the Web Component API (in their site you can see a
gridelement being used). I'll update my comment :DIf Svelte is made of a compiler and is more of a language than anything else, and not a framework, then no Riot (I have considered using, riot and read up on it in the past) is not the same. Riot might be kind of closer to Stencil in some ways
It is. Read about reactive statements. svelte.dev/docs#component-format-s...
As far as I understand, mutate methods like ‘array.push’ won’t trigger updates. Take a look there svelte.dev/tutorial/updating-array...
After push you may write like
array = array😉 This works and even is suggested by tutorialsExactly! But my point is to avoid an additional assignment; I believe the comiler could do it.
Great post