What do you mean by "work"? You can export a mutable variable yes, but why would you? It makes no sense outside of Svelte and it doesn't relate to the rest of the code where you presumably use that variable as if it was set from the outside at the moment you were exporting it or something along those lines.
In the end it is also just a compiler directive for svelte, it doesn't end up in the code the svelte compiler outputs.
Look at this example:
https://svelte.dev/repl/c450c88a415a435485729f4ba88069f1?ver...
If you check the JavaScript output tab on right, this prop declaration in Child.svelte
> export let count = 0;
Has become
> let { count = 0 } = $$props;
Which looks a lot closer to this new rune syntax, so
> does not even remotely work like it would in JS.
Is not true at all, it works a lot like this in JS, or at least a lot more than the "export let" syntax.
Edit:
I want to add to your point here:
> That is, $props is not an object. The string "$props" is a compile-time directive that declares myProp to be a prop. It's not destructuring $props, it's declaring myProp. "$props" is a magic incantation defined within the Svelte compiler.
I get you on this!
I wasn't aware it worked like this and replaces the $$Props interface [1] which I am using to declare component props at the moment. I understand your point and I agree that parsing required props and such out of this destructuring assignment is a bit magical, but to be honest in my view not significantly more magical than the rest of Svelte.
[1] https://svelte-5-preview.vercel.app/docs/runes#$props-what-t...
