Utility Types | Vue.js

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<T>
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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<Book>,
      required: true
    }
  }
}

See also Guide - Typing Component Props

MaybeRef<T>
​

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

Only supported in 3.3+.
MaybeRefOrGetter<T>
​

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

Only supported in 3.3+.
ExtractPropTypes<T>
​

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<typeof propsOptions>
// {
//   foo?: string,
//   bar: boolean,
//   baz: number,
//   qux: number
// }
ExtractPublicPropTypes<T>
​

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<typeof propsOptions>
// {
//   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
<div style={ { '--bg-color': 'blue' } }>
html
<div :style="{ '--bg-color': 'blue' }"></div>

TIP

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

See also

SFC <style> tags support linking CSS values to dynamic component state using the v-bind CSS function. This allows for custom properties without type augmentation.

v-bind() in CSS