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May 23, 2025
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docs: move some $state information around #15969

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docs: move some `$state` information around
Rich-Harris May 20, 2025
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Update documentation/docs/02-runes/02-$state.md
Rich-Harris May 21, 2025
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8 changes: 5 additions & 3 deletions documentation/docs/02-runes/02-$state.md
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Expand Up @@ -20,8 +20,6 @@ Unlike other frameworks you may have encountered, there is no API for interactin

If `$state` is used with an array or a simple object, the result is a deeply reactive _state proxy_. [Proxies](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) allow Svelte to run code when you read or write properties, including via methods like `array.push(...)`, triggering granular updates.

> [!NOTE] Class instances are not proxied. You can create [reactive state fields](#Classes) on classes that you define. Svelte provides reactive implementations of built-ins like `Set` and `Map` that can be imported from [`svelte/reactivity`](svelte-reactivity).

State is proxified recursively until Svelte finds something other than an array or simple object. In a case like this...

```js
Expand Down Expand Up @@ -67,7 +65,7 @@ todos[0].done = !todos[0].done;

### Classes

You can also use `$state` in class fields (whether public or private), or as the first assignment to a property immediately inside the `constructor`:
Class instances are not proxied. Instead, you can use `$state` in class fields (whether public or private), or as the first assignment to a property immediately inside the `constructor`:

```js
// @errors: 7006 2554
Expand Down Expand Up @@ -121,6 +119,8 @@ class Todo {
}
```

> Svelte provides reactive implementations of built-in classes like `Set` and `Map` that can be imported from [`svelte/reactivity`](svelte-reactivity).

## `$state.raw`

In cases where you don't want objects and arrays to be deeply reactive you can use `$state.raw`.
Expand All @@ -145,6 +145,8 @@ person = {

This can improve performance with large arrays and objects that you weren't planning to mutate anyway, since it avoids the cost of making them reactive. Note that raw state can _contain_ reactive state (for example, a raw array of reactive objects).

As with `$state`, you can declare class fields using `$state.raw`.

## `$state.snapshot`

To take a static snapshot of a deeply reactive `$state` proxy, use `$state.snapshot`:
Expand Down