charging-cabinet/software/h5-uniapp/.agents/skills/vue/references/features-script-setup.md

name, description

name	description
script-setup	Compile-time syntactic sugar for Composition API in SFCs

Script Setup

<script setup> is the recommended syntax for Composition API in Single-File Components.

Basic Syntax

<script setup lang="ts">
import { ref } from 'vue'

const count = ref(0)

function increment() {
  count.value++
}
</script>

<template>
  <button @click="increment">{{ count }}</button>
</template>

Benefits

• Less boilerplate (no export default, no return)
• TypeScript type inference
• Better runtime performance
• Better IDE support

Top-Level Bindings

All top-level bindings are automatically available in template:

<script setup lang="ts">
// Variables
const msg = 'Hello'

// Imports
import { capitalize } from './helpers'
import MyComponent from './MyComponent.vue'

// Functions
function greet() {
  console.log(msg)
}
</script>

<template>
  <MyComponent />
  <p>{{ capitalize(msg) }}</p>
  <button @click="greet">Greet</button>
</template>

Compiler Macros

These are available without import:

• defineProps() - declare props
• defineEmits() - declare emits
• defineModel() - declare v-model (3.4+)
• defineExpose() - expose public instance properties
• defineOptions() - declare component options (3.3+)
• defineSlots() - type slot props (3.3+)
• withDefaults() - provide prop defaults

Using Components

Import and use directly without registration:

<script setup lang="ts">
import MyComponent from './MyComponent.vue'
import { MyButton } from './components'
</script>

<template>
  <MyComponent />
  <MyButton />
</template>

Dynamic Components

<script setup lang="ts">
import Foo from './Foo.vue'
import Bar from './Bar.vue'
</script>

<template>
  <component :is="condition ? Foo : Bar" />
</template>

Recursive Components

SFCs can reference themselves by filename:

<!-- FooBar.vue can use <FooBar/> in its template -->

Custom Directives

Variables starting with v are available as directives:

<script setup lang="ts">
const vFocus = {
  mounted: (el: HTMLElement) => el.focus()
}
</script>

<template>
  <input v-focus />
</template>

defineExpose()

Components are closed by default. Use defineExpose to expose properties:

<script setup lang="ts">
import { ref } from 'vue'

const count = ref(0)
const publicMethod = () => console.log('called')

defineExpose({
  count,
  publicMethod
})
</script>

Parent can access via template ref:

const childRef = ref()
childRef.value.count // accessible
childRef.value.publicMethod() // accessible

defineOptions() (3.3+)

Declare component options without separate <script> block:

<script setup lang="ts">
defineOptions({
  inheritAttrs: false,
  name: 'CustomName'
})
</script>

defineSlots() (3.3+)

Type slot props for IDE support:

<script setup lang="ts">
const slots = defineSlots<{
  default(props: { msg: string }): any
  header(props: { title: string }): any
}>()
</script>

useSlots() & useAttrs()

Access slots and attrs in script:

<script setup lang="ts">
import { useSlots, useAttrs } from 'vue'

const slots = useSlots()
const attrs = useAttrs()
</script>

Top-Level await

Async setup with Suspense:

<script setup lang="ts">
const data = await fetch('/api/data').then(r => r.json())
</script>

Note: Requires <Suspense> boundary in parent.

Generic Components (TypeScript)

<script setup lang="ts" generic="T extends string | number">
defineProps<{
  items: T[]
  selected: T
}>()
</script>

Multiple generics with constraints:

<script setup lang="ts" generic="T extends Item, U extends string">
import type { Item } from './types'

defineProps<{
  item: T
  label: U
}>()
</script>

Alongside Normal Script

For advanced cases like named exports or one-time side effects:

<script lang="ts">
// Runs once when module is imported
runSideEffect()

export const exportedValue = 'hello'
</script>

<script setup lang="ts">
// Runs for each component instance
</script>