Utility Types#

:::info This page only lists a few commonly used utility types that may need explanation for their usage. For a full list of exported types, consult the source code. :::

PropType\#

Used to annotate a prop with more advanced types when using runtime props declarations.

• Example

```ts import type { PropType } from 'vue'

interface Book { title: string author: string year: number }

export default { props: { book: { // provide more specific type to Object type: Object as PropType, required: true } } } ```

• See also Guide - Typing Component Props

MaybeRef\#

• Only supported in 3.3+

Alias for T | Ref<T>. Useful for annotating arguments of Composables.

MaybeRefOrGetter\#

• Only supported in 3.3+

Alias for T | Ref<T> | (() => T). Useful for annotating arguments of Composables.

ExtractPropTypes\#

Extract prop types from a runtime props options object. The extracted types are internal facing - i.e. the resolved props received by the component. This means boolean props and props with default values are always defined, even if they are not required.

To extract public facing props, i.e. props that the parent is allowed to pass, use ExtractPublicPropTypes.

• Example

```ts const propsOptions = { foo: String, bar: Boolean, baz: { type: Number, required: true }, qux: { type: Number, default: 1 } } as const

type Props = ExtractPropTypes // { // foo?: string, // bar: boolean, // baz: number, // qux: number // } ```

ExtractPublicPropTypes\#

• Only supported in 3.3+

Extract prop types from a runtime props options object. The extracted types are public facing - i.e. the props that the parent is allowed to pass.

• Example

```ts const propsOptions = { foo: String, bar: Boolean, baz: { type: Number, required: true }, qux: { type: Number, default: 1 } } as const

type Props = ExtractPublicPropTypes // { // foo?: string, // bar?: boolean, // baz: number, // qux?: number // } ```

ComponentCustomProperties#

Used to augment the component instance type to support custom global properties.

• Example

```ts import axios from 'axios'

declare module 'vue' { interface ComponentCustomProperties { $http: typeof axios $translate: (key: string) => string } } ```

:::tip Augmentations must be placed in a module .ts or .d.ts file. See Type Augmentation Placement for more details. :::

• See also Guide - Augmenting Global Properties

ComponentCustomOptions#

Used to augment the component options type to support custom options.

• Example

```ts import { Route } from 'vue-router'

declare module 'vue' { interface ComponentCustomOptions { beforeRouteEnter?(to: any, from: any, next: () => void): void } } ```

:::tip Augmentations must be placed in a module .ts or .d.ts file. See Type Augmentation Placement for more details. :::

• See also Guide - Augmenting Custom Options

ComponentCustomProps#

Used to augment allowed TSX props in order to use non-declared props on TSX elements.

• Example

```ts declare module 'vue' { interface ComponentCustomProps { hello?: string } }

export {} ```

tsx // now works even if hello is not a declared prop <MyComponent hello="world" />

:::tip Augmentations must be placed in a module .ts or .d.ts file. See Type Augmentation Placement for more details. :::

CSSProperties#

Used to augment allowed values in style property bindings.

• Example

Allow any custom CSS property

ts declare module 'vue' { interface CSSProperties { [key: `--${string}`]: string } }

```tsx