App.vue：

<template>
  <button @click="isShowDemo = !isShowDemo">切换隐藏/显示</button>
  <Demo v-if="isShowDemo"/>
</template>

<script>
import {ref} from 'vue'
import Demo from './components/Demo'

export default {
  name: 'App',
  components: {Demo},
  setup() {
    let isShowDemo = ref(true)
    return {isShowDemo}
  }
}
</script>

组件Demo.vue：

<template>
  <h2>当前求和为：{{ sum }}</h2>
  <button @click="sum++">点我+1</button>
</template>

<script>
import {ref, onBeforeMount, onMounted, onBeforeUpdate, onUpdated, onBeforeUnmount, onUnmounted} from 'vue'

export default {
  name: 'Demo',

  setup() {
    console.log('setup')
    let sum = ref(0)

    // 通过组合式API的形式去使用生命周期钩子
    onBeforeMount(() => {
      console.log('onBeforeMount')
    })
    onMounted(() => {
      console.log('onMounted')
    })
    onBeforeUpdate(() => {
      console.log('onBeforeUpdate')
    })
    onUpdated(() => {
      console.log('onUpdated')
    })
    onBeforeUnmount(() => {
      console.log('onBeforeUnmount')
    })
    onUnmounted(() => {
      console.log('onUnmounted')
    })

    return {sum}
  },


  // 通过配置项的形式使用生命周期钩子
  beforeCreate() {
    console.log('beforeCreate')
  },
  created() {
    console.log('created')
  },
  beforeMount() {
    console.log('beforeMount')
  },
  mounted() {
    console.log('mounted')
  },
  beforeUpdate() {
    console.log('beforeUpdate')
  },
  updated() {
    console.log('updated')
  },
  beforeUnmount() {
    console.log('beforeUnmount')
  },
  unmounted() {
    console.log('unmounted')
  }
}
</script>