useElementVisibility

跟踪视口中元素的可见性。

¥Tracks the visibility of an element within the viewport.

示例

源代码演练场

Info on the right bottom corner

Target Element (scroll down)

Element outside the viewport

用法

¥Usage

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

const target = useTemplateRef<HTMLDivElement>('target')
const targetIsVisible = useElementVisibility(target)
</script>

<template>
  <div ref="target">
    <h1>Hello world</h1>
  </div>
</template>

rootMargin

如果你希望在元素完全可见之前尽早触发回调，则可以使用 rootMargin 选项（参见 MDN IntersectionObserver/rootMargin）。

¥If you wish to trigger your callback sooner before the element is fully visible, you can use the rootMargin option (See MDN IntersectionObserver/rootMargin).

const targetIsVisible = useElementVisibility(target, {
  rootMargin: '0px 0px 100px 0px',
})

threshold

如果你想控制更新值所需的可见性百分比，可以使用 threshold 选项（参见 MDN IntersectionObserver/threshold）。

¥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).

const targetIsVisible = useElementVisibility(target, {
  threshold: 1.0, // 100% visible
})

组件用法

¥Component Usage

<template>
  <UseElementVisibility v-slot="{ isVisible }">
    Is Visible: {{ isVisible }}
  </UseElementVisibility>
</template>

指令用法

¥Directive Usage

<script setup lang="ts">
import { vElementVisibility } from '@vueuse/components'
import { shallowRef, useTemplateRef } from 'vue'

const target = useTemplateRef<HTMLDivElement>('target')
const isVisible = shallowRef(false)

function onElementVisibility(state) {
  isVisible.value = state
}
</script>

<template>
  <div v-element-visibility="onElementVisibility">
    {{ isVisible ? 'inside' : 'outside' }}
  </div>

  <!-- with options -->
  <div ref="target">
    <div v-element-visibility="[onElementVisibility, { scrollTarget: target }]">
      {{ isVisible ? 'inside' : 'outside' }}
    </div>
  </div>
</template>