# useFeatures API

> Auto-generated API reference for `useFeatures` from @vuetify/v0 (Vuetify0).
> Source of truth: https://0.vuetifyjs.com/api/use-features

## Related

- https://0.vuetifyjs.com/composables/plugins/use-features
- https://0.vuetifyjs.com/composables/plugins/use-permissions
- https://0.vuetifyjs.com/composables/registration/create-tokens

## Functions

### createFeatures

Creates a new features instance.

```ts
(_options?: FeatureOptions) => FeatureContext<FeatureTicketInput, FeatureTicket<FeatureTicketInput>>
```

### createFeaturesContext

```ts
<_E>(_options?: FeaturePluginOptions | undefined) => ContextTrinity<_E>
```

### createFeaturesPlugin

```ts
(_options?: FeaturePluginOptions | undefined) => Plugin
```

### useFeatures

```ts
<_E>(namespace?: string) => _E
```

## Options

| Name | Type | Default | Required | Description |
|---|---|---|---|---|
| `events` | `boolean \| undefined` | `false` | no | Enable event emission for registry operations |
| `reactive` | `boolean \| undefined` | `false` | no | Enable reactive behavior for registry operations |
| `features` | `Record<ID, boolean \| TokenCollection> \| undefined` | — | no | Static feature flags to register. |

## Methods

| Name | Type | Description |
|---|---|---|
| `clear` | `() => void` | Clear the entire registry |
| `has` | `(id: ID) => boolean` | Check if a ticket exists by ID |
| `keys` | `() => readonly ID[]` | Get all registered IDs |
| `browse` | `(value: E["value"]) => readonly ID[] \| undefined` | Browse for an ID(s) by value |
| `lookup` | `(index: number) => ID \| undefined` | Lookup a ticket by index number |
| `get` | `(id: ID) => E \| undefined` | Get a ticket by ID |
| `upsert` | `(id: ID, ticket?: Partial<Z>, event?: string) => E` | Update or insert a ticket by ID |
| `values` | `() => readonly E[]` | Get all values of registered tickets |
| `entries` | `() => readonly [ID, E][]` | Get all entries of registered tickets |
| `unregister` | `(id: ID) => void` | Unregister a ticket by ID |
| `reindex` | `() => void` | Reset the index directory and update all tickets |
| `move` | `(id: ID, toIndex: number) => E \| undefined` | Move a ticket to a new index position |
| `reorder` | `(ids: ID[]) => void` | Reorder the registry to match a canonical permutation of ids in one pass. |
| `seek` | `(direction?: "first" \| "last", from?: number, predicate?: (ticket: E) => boolean) => E \| undefined` | Seek for a ticket based on direction and optional predicate |
| `on` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Listen for registry events |
| `off` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Stop listening for registry events |
| `emit` | `<K extends Extensible<RegistryEventName>>(event: K, data: EventPayload<E, K>) => void` | Emit an event with data |
| `dispose` | `() => void` | Clears the registry and removes all listeners |
| `offboard` | `(ids: ID[]) => Partial<Z>[]` | Offboard multiple tickets at once, returning the input shapes that were removed. |
| `batch` | `<R>(fn: () => R) => R` | Execute operations in a batch, deferring cache invalidation and event emission until complete |
| `reset` | `() => void` | Reset selection state without destroying the registry |
| `selected` | `(id: ID) => boolean` | Check if a ticket is currently selected |
| `apply` | `(values: unknown[], options?: { multiple?: boolean; }) => void` | Apply external values to the model |
| `mandate` | `() => void` | Mandate selected ID based on "mandatory" option |
| `select` | `(ids: ID \| ID[]) => void` | Select one or more Tickets by ID |
| `unselect` | `(ids: ID \| ID[]) => void` | Unselect one or more Tickets by ID |
| `toggle` | `(ids: ID \| ID[]) => void` | Toggle one or more Tickets ON and OFF by ID |
| `mix` | `(ids: ID \| ID[]) => void` | Set one or more Tickets to mixed/indeterminate state by ID |
| `unmix` | `(ids: ID \| ID[]) => void` | Clear mixed/indeterminate state from one or more Tickets by ID |
| `mixed` | `(id: ID) => boolean` | Check if a ticket is in mixed/indeterminate state by ID |
| `selectAll` | `() => void` | Select all selectable (non-disabled) items |
| `unselectAll` | `() => void` | Unselect all items (respects mandatory option) |
| `toggleAll` | `() => void` | Toggle between all selected and none selected |
| `onboard` | `(registrations: Partial<Z>[]) => E[]` | Onboard multiple tickets at once |
| `variation` | `(id: ID, fallback?: unknown) => unknown` | Get the variation value of a feature, or a fallback if not set. |
| `sync` | `(flags: FeaturesAdapterFlags) => void` | Sync feature flags from an external source. |
| `register` | `(registration?: Partial<Z>) => E` | Register a feature (accepts input type, returns output type) |

## Properties

| Name | Type | Description |
|---|---|---|
| `collection` | `ReadonlyMap<ID, E>` | The collection of tickets in the registry |
| `size` | `number` | The number of tickets in the registry |
| `selectedIds` | `Reactive<Set<ID>>` | Set of currently selected ticket IDs |
| `selectedItems` | `ComputedRef<Set<E>>` | Computed Set of selected ticket instances |
| `selectedValues` | `ComputedRef<Set<E["value"] extends Ref<infer U, infer U> ? U : E["value"]>>` | Computed Set of selected ticket values |
| `disabled` | `MaybeRefOrGetter<boolean>` | Disabled state for the entire model instance |
| `multiple` | `MaybeRefOrGetter<boolean>` | Whether the selection allows multiple selections |
| `selectedIndexes` | `ComputedRef<Set<number>>` | — |
| `mixedIds` | `Reactive<Set<ID>>` | Set of mixed/indeterminate ticket IDs |
| `mixedItems` | `ComputedRef<Set<E>>` | Set of mixed/indeterminate ticket instances |
| `isNoneSelected` | `Readonly<Ref<boolean, boolean>>` | Whether no items are currently selected |
| `isAllSelected` | `ComputedRef<boolean>` | Whether all selectable (non-disabled) items are selected |
| `isMixed` | `ComputedRef<boolean>` | Whether some but not all selectable items are selected |