vue3 生命周期 读取dom元素 / 父组件与子组件的生命周期表变化

<template>
  <p> 我是App.vue组件 </p>
  <HelloWorld msg="Hello Vue 3 + Vite"/>
</template>
<script setup lang="ts">


import HelloWorld from "@/components/HelloWorld.vue";
import {onBeforeMount, onBeforeUnmount, onBeforeUpdate, onMounted, onUnmounted, onUpdated} from "vue";
//beforeCreate created beforeMount mounted beforeUpdate updated activated deactivated beforeDestroy destroyed errorCaptured

//beforeCreate created 如果是setup语法糖模式是没有这两个生命周期的，setup去代替
console.log("setup")
//创建
onBeforeMount(() => {
  console.log("onBeforeMount")
})
//创建完成
onMounted(() => {
  console.log("onMounted")
})
//更新组件之前
onBeforeUpdate(() => {
  console.log("onBeforeUpdate")
})
//更新完成
onUpdated(() => {
  console.log("onUpdated")
})
//销毁之前
onBeforeUnmount(() => {
  console.log("onBeforeUnmount")
})
//销毁完成
onUnmounted(() => {
  console.log("onUnmounted")
})



</script>

 先走setup 然后创建之前，创建完成。

创建之前是无法读取dom元素的

<template>
  <p> 我是App.vue组件 </p>
  <div ref="div">{
   
   { div }}</div>
</template>
<script setup lang="ts">


import {onBeforeMount, onBeforeUnmount, onBeforeUpdate, onMounted, onUnmounted, onUpdated, ref} from "vue";
//beforeCreate created beforeMount mounted beforeUpdate updated activated deactivated beforeDestroy destroyed errorCaptured

//beforeCreate created 如果是setup语法糖模式是没有这两个生命周期的，setup去代替
console.log("setup")
const str = ref<String>("123")
const div = ref<HTMLDivElement>()
//创建
onBeforeMount(() => {
  console.log("onBeforeMount",div.value)
})
//创建完成
onMounted(() => {
  console.log("onMounted",div.value)
})
//更新组件之前
onBeforeUpdate(() => {
  console.log("onBeforeUpdate")
})
//更新完成
onUpdated(() => {
  console.log("onUpdated")
})
//销毁之前
onBeforeUnmount(() => {
  console.log("onBeforeUnmount")
})
//销毁完成
onUnmounted(() => {
  console.log("onUnmounted")
})


</script>

读取dom元素方法很简单

  <div ref="div">{
   
   { div }}</div>

const div = ref<HTMLDivElement>()

如何走到update生命周期呢

<template>
  <p> 我是App.vue组件 </p>
  <div ref="div">{
   
   { str }}</div>
  <button @click="change">修改str</button>
</template>
<script setup lang="ts">


import {onBeforeMount, onBeforeUnmount, onBeforeUpdate, onMounted, onUnmounted, onUpdated, ref} from "vue";
//beforeCreate created beforeMount mounted beforeUpdate updated activated deactivated beforeDestroy destroyed errorCaptured

//beforeCreate created 如果是setup语法糖模式是没有这两个生命周期的，setup去代替
console.log("setup")
const str = ref<String>("123")
const div = ref<HTMLDivElement>()
//创建
onBeforeMount(() => {
  console.log("onBeforeMount", div.value)
})
//创建完成
onMounted(() => {
  console.log("onMounted", div.value)
})
//更新组件之前
onBeforeUpdate(() => {
  console.log("onBeforeUpdate")
})
//更新完成
onUpdated(() => {
  console.log("onUpdated")
})
//销毁之前
onBeforeUnmount(() => {
  console.log("onBeforeUnmount")
})
//销毁完成
onUnmounted(() => {
  console.log("onUnmounted")
})

const change = () => {
  str.value = "456"
}

</script>

 使用change 函数修改str即可 

//更新组件之前
onBeforeUpdate(() => {
  console.log("onBeforeUpdate",div.value?.innerText)
})
//更新完成
onUpdated(() => {
  console.log("onUpdated",div.value?.innerText)
})

 销毁之前，与，销毁。

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修改App.vue代码

<template>
  <p> 我是App.vue组件 </p>
  <A v-if="flag"></A>

  <button @click="flag = !flag">创建-销毁</button>
</template>
<script setup lang="ts">


import {onBeforeMount, onBeforeUnmount, onBeforeUpdate, onMounted, onUnmounted, onUpdated, ref} from "vue";
import A from "./components/A.vue";
//beforeCreate created beforeMount mounted beforeUpdate updated activated deactivated beforeDestroy destroyed errorCaptured

//beforeCreate created 如果是setup语法糖模式是没有这两个生命周期的，setup去代替
console.log("setup")
const flag = ref<Boolean>(false)
const str = ref<String>("123")
const div = ref<HTMLDivElement>()
//创建
onBeforeMount(() => {
  console.log("onBeforeMount", div.value)
})
//创建完成
onMounted(() => {
  console.log("onMounted", div.value)
})
//更新组件之前
onBeforeUpdate(() => {
  console.log("onBeforeUpdate", div.value?.innerText)
})
//更新完成
onUpdated(() => {
  console.log("onUpdated", div.value?.innerText)
})
//销毁之前
onBeforeUnmount(() => {
  console.log("onBeforeUnmount")
})
//销毁完成
onUnmounted(() => {
  console.log("onUnmounted")
})

const change = () => {
  str.value = "456"
}

</script>

修改A.vue代码

<template>
  <p> 我是A组件 </p>

</template>
<script setup lang="ts">


import {onBeforeMount, onBeforeUnmount, onBeforeUpdate, onMounted, onUnmounted, onUpdated, ref} from "vue";
//beforeCreate created beforeMount mounted beforeUpdate updated activated deactivated beforeDestroy destroyed errorCaptured

//beforeCreate created 如果是setup语法糖模式是没有这两个生命周期的，setup去代替
console.log("setup")
const str = ref<String>("123")
const div = ref<HTMLDivElement>()
//创建
onBeforeMount(() => {
  console.log("A onBeforeMount", div.value)
})
//创建完成
onMounted(() => {
  console.log("A onMounted", div.value)
})
//更新组件之前
onBeforeUpdate(() => {
  console.log("A onBeforeUpdate", div.value?.innerText)
})
//更新完成
onUpdated(() => {
  console.log("A onUpdated", div.value?.innerText)
})
//销毁之前
onBeforeUnmount(() => {
  console.log("A onBeforeUnmount")
})
//销毁完成
onUnmounted(() => {
  console.log("A onUnmounted")
})

const change = () => {
  str.value = "456"
}

</script>

首次加载

 点击创建

 点击销毁