生命周期

• 按需导入到组件中，且只能在 setup() 函数中使用

vue 2.x	vue 3
beforeCreate	setup
created	setup
beforeMount	onBeforeMount
mounted	onMounted
beforeUpdate	onBeforeUpdate
updated	onUpdated
beforeDestroy	onBeforeUnmount
destroyed	onUnmounted
errorCaptured	onErrorCaptured
renderTriggered	onRenderTriggered

import { onMounted } from 'vue'

setup(){
    onMounted(() => {
      console.log('mounted')
    })
}

• onActivated – 被 keep-alive 缓存的组件激活时调用
• onDeactivated – 被 keep-alive 缓存的组件停用时调用