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Comment by fzaninotto | Hacker News Reader

The precompilation is a nice idea, but I'm not buying the "vanilla JS" argument. The reason why React and other frameworks have a runtime is also because they optimize rendering.

The Svelte doc says: every call to `component.set()` produces a synchronous DOM update. I can already see how this leads to very poor rendering performance in applications with a large number of nested components.

React and the Virtual DOM solved this problem, and that's why web apps today use a lot of components. So until Svelte can demonstrate fitness and speed comparable to React on large apps, it just looks like Yet Another JS Framework.

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We'll publish some benchmarks soon showing how much better Svelte's performance is than React's. There's a lot of misconceptions around virtual DOM diffing.

Changing a single cell in a table with hundreds of rows and a dozen columns would be a good test.

I don't know, it could work. React almost does the same thing actually, except it batches updates occuring in a single event handler, but otherwise, there is nothing optimized about it, except the reconciliation. A limited string template makes reconciliation a non problem.

Haven't studied the SvelteJS documentation but as far as I can reason there is nothing in their idea that prevents them from shielding the DOM behind a lightweight, virtual DOM, ReactJS style. In fact, I'd be slightly disappointed if they don't shield the DOM somehow. It's the #1 bottleneck, after all.

Check the generated code in the REPL, it's straight DOM manipulations.

Hope they have good reasons, then..

The virtual DOM isn't a replacement for the DOM, it's just a string diffing algorithm. It is only needed because of React's "render everywhere" approach, which is a tradeoff sacrificing efficiency for simplicity. If you don't re-render the entire page any time the model changes, you don't need a virtual DOM.

I'd say your mostly right with the one caveat that a virtual DOM also helps out with batching changes to the DOM, but I suppose there are other ways to make that happen.

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