学习Vue3 第六章（认识Ref全家桶）

　　ref

　　　　接受一个内部值并返回一个响应式且可变的 ref 对象。ref 对象仅有一个 .value property，指向该内部值

<template>
  <div>
    <button @click="changeMsg">change</button>
    <div>{{ message }}</div>
  </div>
</template>
 
 
 
<script setup lang="ts">
let message: string = "我是message"
 
const changeMsg = () => {
   message = "change msg"
}
</script>
 
 
<style>
</style>

　　　　isRef

　　　　判断是不是一个ref对象

import { ref, Ref,isRef } from 'vue'
let message: Ref<string | number> = ref("我是message")
let notRef:number = 123
const changeMsg = () => {
  message.value = "change msg"
  console.log(isRef(message)); //true
  console.log(isRef(notRef)); //false
  
}

　　　　shallowRef

　　　　创建一个跟踪自身 .value 变化的 ref，但不会使其值也变成响应式的

<template>
  <div>
    <button @click="changeMsg">change</button>
    <div>{{ message }}</div>
  </div>
</template>
 
 
 
<script setup lang="ts">
import { Ref, shallowRef } from 'vue'
type Obj = {
  name: string
}
let message: Ref<Obj> = shallowRef({
  name: "小满"
})
 
const changeMsg = () => {
  message.value.name = '大满'
}
</script>
 
 
<style>
</style>

　　triggerRef 

　　　　强制更新页面DOM

<template>
  <div>
    <button @click="changeMsg">change</button>
    <div>{{ message }}</div>
  </div>
</template>
 
 
 
<script setup lang="ts">
import { Ref, shallowRef,triggerRef } from 'vue'
type Obj = {
  name: string
}
let message: Ref<Obj> = shallowRef({
  name: "小满"
})
 
const changeMsg = () => {
  message.value.name = '大满'
 triggerRef(message)
}
</script> 
 
 
<style>
</style>

　　customRef

　　　　自定义ref 

<template>
 
  <div ref="div">小满Ref</div>
  <hr>
  <div>
    {{ name }}
  </div>
  <hr>
  <button @click="change">修改 customRef</button>
 
</template>
 
<script setup lang='ts'>
import { ref, reactive, onMounted, shallowRef, customRef } from 'vue'
 
function myRef<T = any>(value: T) {
  let timer:any;
  return customRef((track, trigger) => {
    return {
      get() {
        track()
        return value
      },
      set(newVal) {
        clearTimeout(timer)
        timer =  setTimeout(() => {
          console.log('触发了set')
          value = newVal
          trigger()
        },500)
      }
    }
  })
}
 
 
const name = myRef<string>('小满')
 
 
const change = () => {
  name.value = '大满'
}
 
</script>
<style scoped>
</style>