$inspect shows empty state object using Classes

[hermit99]

Describe the bug

If a Class contains only $state runes, e.g.

class A {
  sa = $state('$inspect shows empty')
}
export const a = new A()

$inspect shows an empty obj. Whereas if it contains methods, etc., $inspect has more information.

Is this expected?

Reproduction

Playground

Logs

No response

System Info

  System:
    OS: Windows 11 10.0.26100
  Binaries:
    Node: 22.11.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.15.3 - C:\Program Files\nodejs\pnpm.CMD
  Browsers:
    Edge: Chromium (131.0.2903.86)
    Internet Explorer: 11.0.26100.1882

Severity

annoyance

[Leonidaz]

looks it's happening in the clone function.

structuredClone fails if an instance contains a method but succeeds if no methods are defined. Svelte relies on the error to return the uncloned instance.

svelte/packages/svelte/src/internal/shared/clone.js

Lines 119 to 127 in ab3290f

	try {
	return /** @type {Snapshot<T>} */ (structuredClone(value));
	} catch (e) {
	if (DEV) {
	paths.push(path);
	}
	return /** @type {Snapshot<T>} */ (value);
	}

not sure what can be done here. maybe just return the uncloned value without even attempting to clone it if it doesn't match any of the known types above (Data, object, Map, Set, etc.)?

Or, if $inspect could take a custom clone function that takes an input and provides a cloned output.

[paoloricciuti]

Btw you can define a toJSON. method to specify how a class should be "snapshotted"

REPL

[hermit99]

Good to know, thanks @paoloricciuti. However that damages the out-of-the-box brevity of $inspect?

[paoloricciuti]

Good to know, thanks @paoloricciuti. However that damages the out-of-the-box brevity of $inspect?

Why? You just need to make sure to add a toJSON method when you create the class if you think you might use that in $inspect...calling $inspect will be as quick as before.