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2 changes: 1 addition & 1 deletion docs/framework/svelte/reference/functions/shallow.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ title: shallow
function shallow<T>(objA, objB): boolean
```

Defined in: [index.svelte.ts:43](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L43)
Defined in: [index.svelte.ts:50](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L50)

## Type Parameters

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8 changes: 4 additions & 4 deletions docs/framework/svelte/reference/functions/usestore.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ title: useStore
function useStore<TState, TSelected>(store, selector?): object
```

Defined in: [index.svelte.ts:10](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L10)
Defined in: [index.svelte.ts:12](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L12)

### Type Parameters

Expand All @@ -25,7 +25,7 @@ Defined in: [index.svelte.ts:10](https://github.com/TanStack/store/blob/main/pac

#### store

`Store`\<`TState`, `any`\>
`MaybeGetter`\<`Store`\<`TState`, `any`\>\>

#### selector?

Expand All @@ -47,7 +47,7 @@ readonly current: TSelected;
function useStore<TState, TSelected>(store, selector?): object
```

Defined in: [index.svelte.ts:14](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L14)
Defined in: [index.svelte.ts:16](https://github.com/TanStack/store/blob/main/packages/svelte-store/src/index.svelte.ts#L16)

### Type Parameters

Expand All @@ -59,7 +59,7 @@ Defined in: [index.svelte.ts:14](https://github.com/TanStack/store/blob/main/pac

#### store

`Derived`\<`TState`, `any`\>
`MaybeGetter`\<`Derived`\<`TState`, `any`\>\>

#### selector?

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19 changes: 13 additions & 6 deletions packages/svelte-store/src/index.svelte.ts
Original file line number Diff line number Diff line change
Expand Up @@ -7,23 +7,26 @@ export * from '@tanstack/store'
*/
export type NoInfer<T> = [T][T extends any ? 0 : never]

type MaybeGetter<T> = T | (() => T)

export function useStore<TState, TSelected = NoInfer<TState>>(
store: Store<TState, any>,
store: MaybeGetter<Store<TState, any>>,
selector?: (state: NoInfer<TState>) => TSelected,
): { readonly current: TSelected }
export function useStore<TState, TSelected = NoInfer<TState>>(
store: Derived<TState, any>,
store: MaybeGetter<Derived<TState, any>>,
selector?: (state: NoInfer<TState>) => TSelected,
): { readonly current: TSelected }
export function useStore<TState, TSelected = NoInfer<TState>>(
store: Store<TState, any> | Derived<TState, any>,
store: MaybeGetter<Store<TState, any>> | MaybeGetter<Derived<TState, any>>,
selector: (state: NoInfer<TState>) => TSelected = (d) => d as any,
): { readonly current: TSelected } {
let slice = $state(selector(store.state))
let slice = $state(selector(toValue(store).state))

$effect(() => {
const unsub = store.subscribe(() => {
const data = selector(store.state)
const actualStore = toValue(store)
const unsub = actualStore.subscribe(() => {
const data = selector(actualStore.state)
if (shallow(slice, data)) {
return
}
Expand All @@ -40,6 +43,10 @@ export function useStore<TState, TSelected = NoInfer<TState>>(
}
}

function toValue<T>(store: T | (() => T)): T {
return typeof store === 'function' ? (store as () => T)() : store
}

export function shallow<T>(objA: T, objB: T) {
if (Object.is(objA, objB)) {
return true
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18 changes: 18 additions & 0 deletions packages/svelte-store/tests/DynamicStore.test.svelte
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
<script lang="ts">
import { Store } from '@tanstack/store'
import { useStore } from '../src/index.svelte.js'

function createStore(count: number) {
return new Store({ count })
}

let store = $state(createStore(0))

const storeVal = useStore(
() => store,
(state) => state.count,
)
</script>

<p>Store: {storeVal.current}</p>
<button onclick={() => (store = createStore(10))}>Update store</button>
9 changes: 9 additions & 0 deletions packages/svelte-store/tests/index.test.ts
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import { render, waitFor } from '@testing-library/svelte'
import { userEvent } from '@testing-library/user-event'
import { shallow } from '../src/index.svelte.js'
import TestBaseStore from './BaseStore.test.svelte'
import DynamicStore from './DynamicStore.test.svelte'
import TestRerender from './Render.test.svelte'

const user = userEvent.setup()
Expand All @@ -26,6 +27,14 @@ describe('useStore', () => {
await user.click(getByText('Update ignored'))
expect(getByText('Number rendered: 2')).toBeInTheDocument()
})

it('allows us to use a dynamic store', async () => {
const { getByText } = render(DynamicStore)
expect(getByText('Store: 0')).toBeInTheDocument()

await user.click(getByText('Update store'))
await waitFor(() => expect(getByText('Store: 10')).toBeInTheDocument())
})
})

describe('shallow', () => {
Expand Down
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