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单独提取自vueuse, 主要是因为uniapp不能使用vueuse 10+版本, 所以独立出该动能给uniapp使用

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category: Component outline: deep

createReusableTemplate

Define and reuse template inside the component scope.

Motivation

It's common to have the need to reuse some part of the template. For example:

<template>
  <dialog v-if="showInDialog">
    <!-- something complex -->
  </dialog>
  <div v-else>
    <!-- something complex -->
  </div>
</template>

We'd like to reuse our code as much as possible. So normally we might need to extract those duplicated parts into a component. However, in a separated component you lose the ability to access the local bindings. Defining props and emits for them can be tedious sometime.

So this function is made to provide a way for defining and reusing templates inside the component scope.

Usage

In the previous example, we could refactor it to:

<script setup>
import { createReusableTemplate } from '@vueuse/core'

const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
</script>

<template>
  <DefineTemplate>
    <!-- something complex -->
  </DefineTemplate>

  <dialog v-if="showInDialog">
    <ReuseTemplate />
  </dialog>
  <div v-else>
    <ReuseTemplate />
  </div>
</template>

• <DefineTemplate> will register the template and renders nothing.
• <ReuseTemplate> will render the template provided by <DefineTemplate>.
• <DefineTemplate> must be used before <ReuseTemplate>.

Note: It's recommended to extract as separate components whenever possible. Abusing this function might lead to bad practices for your codebase.

Options API

When using with Options API, you will need to define createReusableTemplate outside of the component setup and pass to the components option in order to use them in the template.

<script>
import { defineComponent } from 'vue'
import { createReusableTemplate } from '@vueuse/core'

const [DefineTemplate, ReuseTemplate] = createReusableTemplate()

export default defineComponent({
  components: {
    DefineTemplate,
    ReuseTemplate,
  },
  setup() {
    // ...
  },
})
</script>

<template>
  <DefineTemplate v-slot="{ data, msg, anything }">
    <div>{{ data }} passed from usage</div>
  </DefineTemplate>

  <ReuseTemplate :data="data" msg="The first usage" />
</template>

Passing Data

You can also pass data to the template using slots:

• Use v-slot="..." to access the data on <DefineTemplate>
• Directly bind the data on <ReuseTemplate> to pass them to the template

<script setup>
import { createReusableTemplate } from '@vueuse/core'

const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
</script>

<template>
  <DefineTemplate v-slot="{ data, msg, anything }">
    <div>{{ data }} passed from usage</div>
  </DefineTemplate>

  <ReuseTemplate :data="data" msg="The first usage" />
  <ReuseTemplate :data="anotherData" msg="The second usage" />
  <ReuseTemplate v-bind="{ data: something, msg: 'The third' }" />
</template>

TypeScript Support

createReusableTemplate accepts a generic type to provide type support for the data passed to the template:

<script setup lang="ts">
import { createReusableTemplate } from '@vueuse/core'

// Comes with pair of `DefineTemplate` and `ReuseTemplate`
const [DefineFoo, ReuseFoo] = createReusableTemplate<{ msg: string }>()

// You can create multiple reusable templates
const [DefineBar, ReuseBar] = createReusableTemplate<{ items: string[] }>()
</script>

<template>
  <DefineFoo v-slot="{ msg }">
    <!-- `msg` is typed as `string` -->
    <div>Hello {{ msg.toUpperCase() }}</div>
  </DefineFoo>

  <ReuseFoo msg="World" />

  <!-- @ts-expect-error Type Error! -->
  <ReuseFoo :msg="1" />
</template>

Optionally, if you are not a fan of array destructuring, the following usages are also legal:

<script setup lang="ts">
import { createReusableTemplate } from '@vueuse/core'

const {
  define: DefineFoo,
  reuse: ReuseFoo,
} = createReusableTemplate<{ msg: string }>()
</script>

<template>
  <DefineFoo v-slot="{ msg }">
    <div>Hello {{ msg.toUpperCase() }}</div>
  </DefineFoo>

  <ReuseFoo msg="World" />
</template>

<script setup lang="ts">
import { createReusableTemplate } from '@vueuse/core'

const TemplateFoo = createReusableTemplate<{ msg: string }>()
</script>

<template>
  <TemplateFoo.define v-slot="{ msg }">
    <div>Hello {{ msg.toUpperCase() }}</div>
  </TemplateFoo.define>

  <TemplateFoo.reuse msg="World" />
</template>

::: warning Dot notation is not supported in Vue 2. :::

::: warning Passing boolean props without v-bind is not supported. See the Caveats section for more details. :::

Passing Slots

It's also possible to pass slots back from <ReuseTemplate>. You can access the slots on <DefineTemplate> from $slots:

<script setup>
import { createReusableTemplate } from '@vueuse/core'

const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
</script>

<template>
  <DefineTemplate v-slot="{ $slots, otherProp }">
    <div some-layout>
      <!-- To render the slot -->
      <component :is="$slots.default" />
    </div>
  </DefineTemplate>

  <ReuseTemplate>
    <div>Some content</div>
  </ReuseTemplate>
  <ReuseTemplate>
    <div>Another content</div>
  </ReuseTemplate>
</template>

::: warning Passing slots does not work in Vue 2. :::

Caveats

Boolean props

As opposed to Vue's behavior, props defined as boolean that were passed without v-bind or absent will be resolved into an empty string or undefined respectively:

<script setup lang="ts">
import { createReusableTemplate } from '@vueuse/core'

const [DefineTemplate, ReuseTemplate] = createReusableTemplate<{
  value?: boolean
}>()
</script>

<template>
  <DefineTemplate v-slot="{ value }">
    {{ typeof value }}: {{ value }}
  </DefineTemplate>

  <ReuseTemplate :value="true" />
  <!-- boolean: true -->

  <ReuseTemplate :value="false" />
  <!-- boolean: false -->

  <ReuseTemplate value />
  <!-- string: -->

  <ReuseTemplate />
  <!-- undefined: -->
</template>

References

This function is migrated from vue-reuse-template.

Existing Vue discussions/issues about reusing template:

• Discussion on Reusing Templates

Alternative Approaches:

• Vue Macros - namedTemplate
• unplugin-@vueuse/core