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Add comprehensive reference documentation for: - Vitest: environments, projects/workspaces, type testing, vi utilities - Pinia: HMR, Nuxt integration, SSR setup - Vue: built-in components (Transition, Teleport, Suspense, KeepAlive) and advanced directives
124 lines
2.8 KiB
Markdown
124 lines
2.8 KiB
Markdown
---
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category: Elements
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---
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# useElementVisibility
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Tracks the visibility of an element within the viewport.
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## Usage
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```vue
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<script setup lang="ts">
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import { useElementVisibility } from '@vueuse/core'
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import { useTemplateRef } from 'vue'
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const target = useTemplateRef('target')
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const targetIsVisible = useElementVisibility(target)
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</script>
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<template>
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<div ref="target">
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<h1>Hello world</h1>
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</div>
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</template>
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```
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### rootMargin
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If you wish to trigger your callback sooner before the element is fully visible, you can use
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the `rootMargin` option (See [MDN IntersectionObserver/rootMargin](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/rootMargin)).
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```ts
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import { useElementVisibility } from '@vueuse/core'
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// ---cut---
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const targetIsVisible = useElementVisibility(target, {
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rootMargin: '0px 0px 100px 0px',
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})
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```
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### threshold
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If you want to control the percentage of the visibility required to update the value, you can use the `threshold` option (See [MDN IntersectionObserver/threshold](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver#threshold)).
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```ts
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const targetIsVisible = useElementVisibility(target, {
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threshold: 1.0, // 100% visible
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})
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```
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## Component Usage
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```vue
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<template>
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<UseElementVisibility v-slot="{ isVisible }">
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Is Visible: {{ isVisible }}
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</UseElementVisibility>
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</template>
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```
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## Directive Usage
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```vue
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<script setup lang="ts">
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import { vElementVisibility } from '@vueuse/components'
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import { shallowRef, useTemplateRef } from 'vue'
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const target = useTemplateRef('target')
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const isVisible = shallowRef(false)
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function onElementVisibility(state) {
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isVisible.value = state
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}
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</script>
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<template>
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<div v-element-visibility="onElementVisibility">
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{{ isVisible ? 'inside' : 'outside' }}
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</div>
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<!-- with options -->
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<div ref="target">
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<div v-element-visibility="[onElementVisibility, { scrollTarget: target }]">
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{{ isVisible ? 'inside' : 'outside' }}
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</div>
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</div>
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</template>
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```
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## Type Declarations
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```ts
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export interface UseElementVisibilityOptions
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extends
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ConfigurableWindow,
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Pick<UseIntersectionObserverOptions, "rootMargin" | "threshold"> {
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/**
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* Initial value.
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*
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* @default false
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*/
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initialValue?: boolean
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/**
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* The element that is used as the viewport for checking visibility of the target.
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*/
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scrollTarget?: UseIntersectionObserverOptions["root"]
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/**
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* Stop tracking when element visibility changes for the first time
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*
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* @default false
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*/
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once?: boolean
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}
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export type UseElementVisibilityReturn = ShallowRef<boolean>
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/**
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* Tracks the visibility of an element within the viewport.
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*
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* @see https://vueuse.org/useElementVisibility
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*/
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export declare function useElementVisibility(
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element: MaybeComputedElementRef,
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options?: UseElementVisibilityOptions,
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): UseElementVisibilityReturn
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```
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