That aside, the idea of svelte is cool, and i'm happy they're continuing to build on that. Excited to see what comes out of this!
When look at fiber and react-reconciler, it seems to me react is already contemplating the future. The reconciler especially.
The biggest reason for me to prefer it: JSX is a simple but elegant solution to a decades old problem. A function signature was all it took to allow it to become cross platform and independent of the browser. A template engine comes at the expense of simplicity and flexibility. It needs so many abstraction and circumventions to function, injecting scope, evals, parsers, foreign syntax ... and for what, it most certainly doesn't make things easier.
You can skip JSX and write `React.createElement` everywhere, and nothing will change. Your code remains Javascript code. Unlike whatever svelte/sapper is. More details in a different comment: https://news.ycombinator.com/item?id=16053685
Nothing about svelte is "just HTML with styles and scripts". It's a yet another custom weird templating language with its own custom magic binding rules and a Javascript-like scripting language which breaks all assumptions about Javascript (methods/properties hoisting, invalid scoping rules, automatic data/variable injection etc. etc. etc.). And it's also just strings everywhere. And magic strings (as in "add $ to tell svelte the property comes from a store").
Ok, I'll level with you — that's not actually doing the same thing as the Fiber version. But that's it's basically impossible to accidentally slow down your Svelte app in the same way as the Fiber demo depends on. Fiber doesn't really speed things up so much as it prevents bad code slowing things down.
The innovation isn't templates (though these aren't your grandad's templates), it's compiling those templates to lean, memory-efficient JS code that doesn't depend on virtual DOM reconciliation or anything like that.
As for a lean dom representation, i have never seen or heard of memory related problems regarding v-dom. And won't byte-code make it leaner in any case? React-compiled is already being tested.
Mind you, I don't actually know if Svelte avoids this problem, but a statement like "doesn't depend on virtual DOM reconciliation or anything like that" kind of implies that it defaults to less work.
Who would intentionally use an older version of a framework, where the upgrade path breaks compatibility?
Angular 1.x is in essence, dead. It's just going to take a long time to go away.