vue2/vue3 Composition Api 常用工具集， @vueuse/core 之核心函数 elements 实践

VueUse是一款基于组合式API的函数集合。

VueUse不是Vue.use，它是为Vue 2和3服务的一套Vue Composition API的常用工具集，是目前世界上Star最高的同类型库之一。它的初衷就是将一切原本并不支持响应式的JS API变得支持响应式，省去程序员自己写相关代码。

useActiveElement

响应式 document.activeElement

<script lang="ts" setup>
import { useActiveElement } from '@vueuse/core'
import { watch, ref } from 'vue'

const activeElement = useActiveElement()

const element: any = ref(null)
watch(activeElement, (el) => {
  element.value = el
})
</script>

<template>
  <div class="use-active-element">
    <input id="1" value="1" />
    <input id="2" value="2" /><br />
    Active element is {{ element?.id }}
  </div>
</template>

useDocumentVisibility

响应式跟踪 document.visibilityState

最大最小化页面或者切换浏览器页页签触发状态

<script lang="ts" setup>
import { useDocumentVisibility } from '@vueuse/core'
import { watch, ref, onUnmounted } from 'vue'

const visibility = useDocumentVisibility()

const hello = ref('最小化页面或切换标签然后返回！')
const unwatch = watch(visibility, (current, previous) => {
  if (current === 'visible' && previous === 'hidden') {
    hello.value = '欢迎回家！'
  }
})

onUnmounted(() => {
  unwatch()
})
</script>

<template>
  <div class="use-document-visibility">
    {{ hello }}
  </div>
</template>

useDraggable

使元素可拖拽。

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

const el = ref<HTMLElement | null>(null)
const { x, y, style } = useDraggable(el, {
  initialValue: { x: 40, y: 40 },
})
</script>

<template>
  <div class="use-draggable" ref="el" :style="style" style="position: fixed;">
    <div class="title">标题</div>
    我的位置：{{ x }}, {{ y }}
  </div>
</template>

<style scoped lang="less">
.use-draggable {
  border: 1px solid #e5e5e5;
  border-radius: 4px;
  background: #fff;
  color: #333;
  padding: 10px 20px;
  .title {
    line-height: 32px;
    font-size: 14px;
    font-weight: bold;
  }
}
</style>

useDropZone

创建一个可以放置文件的区域。

<script lang="ts" setup>
import { useDropZone } from '@vueuse/core'
import { ref } from 'vue'
import stateVue from '../../../views/state.vue'

const dropZoneRef = ref<HTMLDivElement>()

const state = ref({})

function onDrop(files: File[] | null) {
  state.value = files[0]
}

const { isOverDropZone } = useDropZone(dropZoneRef, onDrop)
</script>

<template>
  <div class="drop-zone-container" ref="dropZoneRef">
    拖拽文件放在这里
    <br />
    name: {{ state.name }}<br />
    size: {{ state.size }}<br />
    type: {{ state.type }}<br />
  </div>
</template>

<style lang="less" scoped>
.drop-zone-container {
  background: #e5e5e5;
  border: 1px solid #ccc;
  padding: 10px;
  border-radius: 4px;
  width: 200px;
  height: 200px;
  color: #333;
}
</style>

useElementBounding

让HTML元素的bounding box 响应式

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

const el = ref(null)
const options = {
  reset: true, // 组件卸载时重置边界信息
  windowResize: true, // 监听窗口大小调整事件
  windowScroll: true, // 监听窗口滚动事件
  immediate: true, // 组件挂载时立即调用
}
const {
  x,
  y,
  top,
  right,
  bottom,
  left,
  width,
  height,
} = useElementBounding(el, options)
</script>

<template>
  <div ref="el" class="use-element-bounding">
    位置信息：<br />
    x: {{ x }}<br />
    y: {{ y }}<br />
    top: {{ top }}<br />
    right: {{ right }} <br />
    bottom: {{ bottom }}<br />
    width: {{ width }}<br/>
    height: {{ height }}<br/>
  </div>
</template>

<style lang="less" scoped>
.use-element-bounding {
  background: #e5e5e5;
  border: 1px solid #ccc;
  padding: 10px;
  border-radius: 4px;
  width: 200px;
  height: 200px;
  color: #333;
}
</style>

useElementSize

元素尺寸大小响应式. ResizeObserver MDN

大小默认不包含 padding、border

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

const el = ref(null)
const {
  width,
  height,
} = useElementSize(el)
</script>

<template>
  <div ref="el" class="use-element-size">
    width: {{ width }}<br/>
    height: {{ height }}<br/>
  </div>
</template>

<style lang="less" scoped>
.use-element-size {
  background: #e5e5e5;
  border: 1px solid #ccc;
  padding: 10px;
  border-radius: 4px;
  width: 200px;
  height: 200px;
  color: #333;
}
</style>

useElementVisibility

跟踪元素在视口中的可见性。

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

const target = ref(null)
const targetIsVisible = useElementVisibility(target)
</script>

<template>
  <div class="use-element-visiblity">
    <div ref="target">向下滚动到可视区域</div>
    <div class="tips-zone">
      提示内容{{ targetIsVisible }}
    </div>
  </div>
</template>

<style lang="less">
.tips-zone {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 9;
  border: 2px dashed #ccc;
  padding: 20px;
}
</style>

useIntersectionObserver

响应式监听目标元素的可见性。

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

const target = ref(null)
const targetIsVisible = ref(false)
const { stop } = useIntersectionObserver(
  target,
  ([{ isIntersecting }], observerElement) => {
    targetIsVisible.value = isIntersecting
  }
)
</script>

<template>
  <div class="use-intersection-observer">
    <div class="box">
      <div class="p1">向下滚动</div>
      <div class="p2" ref="target">
        监听可视区域内容
      </div>
      <div class="p3">最底部</div>
    </div>
    <div class="tip">元素在窗口内 {{ targetIsVisible }}</div>
  </div>
</template>

<style lang="less">
.use-intersection-observer {
  .box {
    border: 2px dashed #ccc;
    height: 100px;
    overflow-y: auto;
    padding: 20px;
    .p1, .p3 {
      padding: 30px;
    }
    .p2 {
      margin-top: 100px;
    }
  }
}
</style>

useMouseInElement

响应式获取鼠标相对于元素的位置

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

const target = ref(null)
const {
  x,
  y,
  sourceType,
  elementX,
  elementY,
  elementPositionX,
  elementPositionY,
  elementHeight,
  elementWidth,
  isOutside
} = useMouseInElement(target)
</script>

<template>
  <div ref="el" class="use-mouse-in-element">
    <div ref="target" class="content">相对内容</div>
    位置信息：<br />
    x: {{ x }}<br />
    y: {{ y }}<br />
    sourceType: {{ sourceType }}<br />
    elementX: {{ elementX }}<br />
    elementY: {{  elementY }}<br />
    elementPositionX: {{ elementPositionX }}<br />
    elementPositionY: {{ elementPositionY }}<br />
    elementHeight: {{ elementHeight }}<br />
    elementWidth: {{  elementWidth }}<br />
    isOutside: {{  isOutside }}<br />
  </div>
</template>

<style lang="less" scoped>
.use-mouse-in-element {
  background: #e5e5e5;
  border: 1px solid #ccc;
  padding: 10px;
  border-radius: 4px;
  width: 400px;
  color: #333;
  .content {
    color: #fff;
    background: #000;
    padding: 40px;
  }
}
</style>

useMutationObserver

监听DOM树修改 MutationObserver MDN

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

const targetElement = ref(null)
const messages = ref([])

// 使用useMutationObserver自定义钩子
useMutationObserver(targetElement, (mutations) => {
  console.log('DOM元素发生变化:', mutations)
  if (mutations[0])
    messages.value.push(mutations[0].attributeName)
  }, {
    attributes: true,
  });

  // 改变DOM元素的内容
  const changeElement = () => {
    targetElement.value.style.color = '#000'
  }

</script>

<template>
  <div>
    <h2>DOM元素监视器</h2>
    <div ref="targetElement" style="background-color: #ccc;">
      监视的元素
    </div>
    <button @click="changeElement">改变元素</button>
    {{ messages }}
  </div>
</template>

useResizeObserver

监听元素内容和边框尺寸的变化。

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

const el = ref(null)
const text = ref('')

useResizeObserver(el, (entries) => {
  const entry = entries[0]
  const { width, height } = entry.contentRect
  text.value = `width: ${width}, height: ${height}`
})

</script>

<template>
  <div class="use-resize-observer" ref="el">
    {{ text }}
  </div>
</template>

useWindowFocus

使用 window.onfocus 和 window.onblur 事件响应式跟踪窗口焦点。

离开窗口，切到其它页签触发

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

const focused = useWindowFocus()
</script>

<template>
  <div class="use-window-focus">
    窗口是否聚焦 {{ focused }}
  </div>
</template>

useWindowScroll

响应式获取窗口的滚动位置。

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

const { x, y } = useWindowScroll()
</script>

<template>
  <div class="use-window-scroll">
    x: {{ x }}, y: {{ y }}
  </div>
</template>

useWindowSize

响应式获取窗口尺寸

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

const { width, height } = useWindowSize()
</script>

<template>
  <div class="use-window-size">
    width: {{ width }}, height: {{ height }}
  </div>
</template>