学习Vue3——Ref全家桶

news2025/1/10 21:27:21

参考地址

小满Vue3视频

ref

创造响应式对象

这样修改num的值是可以，但是页面展示不正常，因为这不是响应式的，无法被vue追踪

<template>
  <div>
    {{ num }}
  </div>
  <button @click="change">修改</button>
</template>

<script setup lang="ts">
let num = 1
const change = () => {
  num++
  console.log(`num:${num}`)
}
</script>

可以使用ref来包装这个值，完成响应
注意被ref包装之后需要.value 来进行赋值

<template>
  <div>
    {{ num }}
  </div>
  <button @click="change">修改</button>
</template>
<script setup lang="ts">
import { ref } from 'vue'
let num = ref(1)
const change = () => {
  num.value++
  console.log(`num:${num.value}`)
}
</script>

获取元素dom

<template>
  <div ref="dom" @click="getDom">我是dom</div>
</template>
<script setup lang="ts">
import { ref } from 'vue'
const dom = ref<HTMLDivElement>()
const getDom = () => {
  console.log(dom.value?.innerText) // 我是dom
}
</script>

shallowRef

ref是深层次的响应，shallowRef是浅层次的比较，修改其属性是非响应式的

<template>
  <div>Ref: {{ title }}</div>
  <button @click="changeTitle">Ref按钮</button>
  <hr />
  <div>shallowRef:{{ header }}</div>
  <button @click="changeName">shallowRef按钮</button>
  <hr />
</template>
<script setup lang="ts">
import { ref, shallowRef } from 'vue'
let title = ref({ name: 'hello world' })
let header = shallowRef({ name: 'zs' })

const changeTitle = () => {
  title.value.name = 'I am coming'
}

const changeName = () => {
  header.value.name = 'ls'
  console.log(header) // 值已经改变，但是页面不会响应
}
</script>

修改value是可以被监听到的

const changeName = () => {
// 这样写可以导致shallowRef的视图更新
  header.value = {
    name: 'ls'
  }
  console.log(header) 
}

ref与shallowRef不能写在一起，不然会影响shallowRef 造成视图的更新
因为ref的更新底层调用了triggerRef

const changeName = () => {
// 这样写会导致shallowRef的视图更新
  title.value.name = 'I am coming'
  header.value.name = 'ls'
  console.log(header) 
}

triggerRef

强制更新页面DOM

import { ref, shallowRef, triggerRef } from 'vue'
const changeName = () => {
  header.value.name = 'ls'
  // 这样写也会导致shallowRef的视图更新
  triggerRef(header)
  console.log(header)
}

customRef

customRef 是个工厂函数要求我们返回一个对象并且实现 get 和 set 适合去做防抖之类的

<template>
  <div>customRef:{{ obj }}</div>
  <button @click="changeObj">customRef按钮</button>
</template>
<script setup lang="ts">
import { customRef } from 'vue'

function MyRef<T>(value: T) {
  let timer: any
  return customRef((track, trigger) => {
    return {
      get() {
        track()
        return value
      },
      set(newVal) {
        clearTimeout(timer)
        timer = setTimeout(() => {
          value = newVal
          timer = null
          trigger()
        }, 1000)
      }
    }
  })
}
const obj = MyRef<string>('zs')
const changeObj = () => {
  obj.value = 'customRef'
  console.log(obj)
}
</script>

isRef

用于判断是否为ref对象

import { ref, isRef, shallowRef } from 'vue'
let num = ref(1)
let header = shallowRef({ name: 'zs' })
let message = '123'
console.log(isRef(num), isRef(message), isRef(header)) // true false true