The point is that A) that's a framework and B) that requires you to compile Svelte files. If you want to write declarative UI in pure JS then you need the brow

The point is that A) that's a framework and B) that requires you to compile Svelte files. If you want to write declarative UI in pure JS then you need the browser to do these DOM optimisations for you, and diffing the changes is the way to do that.