This is always a personal judgement, but here's my personal list:
- I find it so much easier to understand. I don't have to useState/useEffect/whatever, I just assign variables and the component re-renders
the relevant parts whenever I assign a new value.
- Styling is "just" CSS. No messing around with CSS-in-JS libraries and their various ways of being invoked. The CSS is automatically scoped to your component without you having to think about it (though IMO there’s work to do there with CSS variables and the like)
- The end-user bundle is so much smaller. This doesn't matter so much if you're creating a giant web app (e.g. Gmail) but I often work on smaller sites and it's very gratifying for users to only have to download ~20KB of JS rather than the hundreds (if not megabytes) you'd get with React. Has a positive impact on page performance scores, SEO etc too.
> I find it so much easier to understand. I don't have to useState/useEffect/whatever, I just assign variables and the component re-renders the relevant parts whenever I assign a new value.
What's frustrating for me is that I'm so used to thinking in hooks that when I first gave Svelte a try, it didn't click. And I knew that was wrong, lol. The release of Svelte 4 is good timing, I might have a use-case at work for a small project to try it out, so I'm going to give it another shot.
I find reactive systems to be at least as complicated as React's declarative model. I was glad to move on from Knockout more than a decade ago and Svelte is conceptually the same thing in how they work, but with a different proprietary syntax and a faster renderer.
I also don't understand the styling complaint. React devs used "just CSS" for years before some of them started pushing for CSS-in-JS. In fact, SCSS/CSS is the default for the still nearly ubiquitous create react app system.
End-user bundle argument is a red herring. What is true for "hello world" isn't true for large applications. The overhead of React is a one-time payment while each new Svelte component drags along all the code needed to support it (copying similar code over and over).
React's F + N * C (where F is framework size, N is component count, and C is average component size) is smaller for large values of N than Svelte's N * (F + C) approach.
That N is very large. E.g. here's a page that talks about it: https://github.com/halfnelson/svelte-it-will-scale. I'll note that was done with Svelte 3 and that with Svelte 4 components are at least 10% smaller, so it's actually even better than that. SvelteKit is also very efficient at JS splitting per-route thanks to Vite. It ensures only the JS that is necessary for a page is loaded and you're extremely unlikely to be using anywhere near that many components. Based on the article above, you'd have to have three entire sites worth of components on a single page.
What code does Svelte use internally vs what code winds up compiled into your components? Last I checked, MOST of the code wound up in your components. In fact, this was their entire argument for why people should use Svelte when it launched.
Just look at their "Hello World" application on the Svelte website. 5 lines of code transform into 45 lines of code.
- I find it so much easier to understand. I don't have to useState/useEffect/whatever, I just assign variables and the component re-renders the relevant parts whenever I assign a new value.
- Styling is "just" CSS. No messing around with CSS-in-JS libraries and their various ways of being invoked. The CSS is automatically scoped to your component without you having to think about it (though IMO there’s work to do there with CSS variables and the like)
- The end-user bundle is so much smaller. This doesn't matter so much if you're creating a giant web app (e.g. Gmail) but I often work on smaller sites and it's very gratifying for users to only have to download ~20KB of JS rather than the hundreds (if not megabytes) you'd get with React. Has a positive impact on page performance scores, SEO etc too.