Why does proxy() internally create a copy of the object?

[pastelmind]

I'm referring to this:

valtio/src/vanilla.ts

Lines 244 to 246 in a828b04

	const baseObject = Array.isArray(initialObject)
	? []
	: Object.create(Object.getPrototypeOf(initialObject))

Why does Valtio create a copy of the original object passed to proxy()? Not trying to argue, just curious about the design decision.

cf. Vue 3's reactivity system simply wraps the Proxy over the original object.

[pastelmind]

Is it because Valtio wants to handle non-configurable, non-writable properties?

FWIW, Vue 3 can't handle them because they wrap the target object directly.

[dai-shi]

It's the design choice.
We assume the initial object as immutable objects, and do not modify it. So that proxy() is being a pure function.
We've discussed this somewhere else, and because this behavior isn't configurable, I'm planning to change the design in the next major version: #703

[orange4glace]

I'm not fully understand about valtio but I thought that valtio is superset of Proxy of ES6 when I first saw.
The Proxy uses the original object and it is meant-to-be used to mutable object. For example,

const origin = {};
const proxy = new Proxy(origin, {});
proxy.x = 10;
origin.x === 10 // true

From that point of view, I think using the initial object makes more sense, IMHO.