Bind to a Map() Object not possible

[firewave-remo]

Describe the bug
I am not sure if this should work or if it's a feature request in the end.

It is easily possible to bind to a normal Object {} with "keys", but it seems not to be possible if i have a Map object. I have tried to simplify the repl as much as possible.

Works:

	const id = 1;
	
	const obj = {};
	obj[id] = {x: 0, y: 0};
...
<input type="range" min="0" max="100" bind:value={obj[id].x} />

Does not work:

	const map = new Map();
	map.set(id, {x: 50, y: 50});
...
<input type="range" min="0" max="100" bind:value={map.get(id).x} />

Full repl see link.

To Reproduce
Repl:
https://svelte.dev/repl/947950a2c1754c20a86c39f34924485a?version=3.30.0

Expected behavior
Can bind to object stored in Map

Severity
Low

Context
In my real Application the Map object is a Store with lots of objects in it which I access by key. I wanted to do a performance comparison between Objects and Maps for my specific case.

[sphinxc0re]

Same thing with group binds and Set https://svelte.dev/repl/805638d52bc74bd38aac2655dd3a6455?version=3.30.0

[firewave-remo]

@sphinxc0re The group binds and Set makes kind of sense that they don't work because you are not working against an array with normal array methods. I think this cannot work.

My case is different because i want to directly change the value of a specific property.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ecstrema]

Still an important issue IMO

[besstiolle]

i would be glad to see this feature in a close futur too ;)

[Riizade]

Recently spent quite a bit of time debugging an issue with this as the root.
This would be an excellent feature to add.

However, in the meantime, I would appreciate a warning or error from the Svelte compiler for map[x] or map.get(x) showing up in a binding that lets users know that it doesn't work.

(I realize map[x] also doesn't do what users of other languages might expect, but somewhat surprisingly the Svelte + TypeScript compiler doesn't catch that mistake either).