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defineProp

Stability: experimental ⚠️ Experimental feature, use at your risk

Declare single prop one by one using defineProp.

FeaturesSupported
Vue 3
Nuxt 3
Vue 2
TypeScript / Volar

WARNING

defineProp can not be used in the same file as type-declared defineProps.

Configuration

ts
VueMacros({
  defineProp: {
    /**
     * 'kevinEdition' | 'johnsonEdition'
     * @default 'kevinEdition'
     */
    edition: 'kevinEdition',
  },
})

Volar

jsonc
// tsconfig.json
{
  // ...
  "vueCompilerOptions": {
    "plugins": [
      "@vue-macros/volar/define-prop",
      // ...more feature
    ],
    // "kevinEdition" | "johnsonEdition" | false
    "experimentalDefinePropProposal": "kevinEdition",
  },
}

Kevin's Edition (Default)

API Reference

ts
defineProp<T>(propName)
defineProp<T>(propName, options)

// propName parameter can be optional,
// and will be inferred from variable name
const propName = defineProp<T>()

Basic Usage

vue
<script setup>
// Declare prop
const 
count
=
defineProp
('count')
// Infer prop name from variable name const
value
=
defineProp
()
// access prop value
console
.
log
(
count
.
value
)
</script>

With Options

vue
<script setup lang="ts">
// Declare prop with options
const 
count
=
defineProp
('count', {
type
:
Number
,
required
: true,
default
: 0,
validator
: (
value
: number) =>
value
< 20,
}) </script>

TypeScript

vue
<script setup lang="ts">
// Declare prop of type number and infer prop name from variable name
const 
count
=
defineProp
<number>()
count
.
value
// Declare prop of TS type boolean with default value const
disabled
=
defineProp
<boolean>('disabled', {
default
: true })
disabled
.
value
</script>

With Reactivity Transform

ts
const foo = $defineProp<string>('foo')
//    ^? type: string | undefined

const bar = $(defineProp('bar', { default: 'bar' }))
//    ^? type: string

Johnson's Edition

API Reference

ts
// the prop name will be inferred from variable name
const propName = defineProp<T>()
const propName = defineProp<T>(defaultValue)
const propName = defineProp<T>(defaultValue, required)
const propName = defineProp<T>(defaultValue, required, rest)

Basic Usage

vue
<script setup>
// declare prop `count` with default value `0`
const 
count
=
defineProp
(0)
// declare required prop `disabled` const
disabled
=
defineProp
(
undefined
, true)
// access prop value
console
.
log
(
count
.
value
,
disabled
.
value
)
</script>

With Options

vue
<script setup lang="ts">
// Declare prop with options
const 
count
=
defineProp
(0, false, {
type
:
Number
,
validator
: (
value
: number) =>
value
< 20,
}) </script>

TypeScript

vue
<script setup lang="ts">
const 
count
=
defineProp
<number>()
count
.
value
// Declare prop of TS type boolean with default value const
disabled
=
defineProp
<boolean>(true)
disabled
.
value
</script>

With Reactivity Transform

vue
<script setup lang="ts">
const foo = $defineProp<number>()
//    ^? type: number | undefined

const bar = $(defineProp(0, true))
//    ^? type: number
</script>

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Changelog