vue 的子元件有兩種方式：同步和非同步，在這兩種引入方式下，父子元件載入的順序也是不一樣的。

同步引入

 import Page from '@/components/page'

非同步引入

const Page = () => import('@/components/page');
//  或者：
const Page = resolve => require(['@/components/page'], page);

同步引入時生命週期順序為：

App.vue

<template>
  <div id="app">
    <New />  <!-- 子元件一 -->
    <Page /> <!-- 子元件二 -->
    <router-view/>
  </div>
</template>
<script>
import Page 
 
from '@/components/page' // 同步方式引入
import New from '@/components/new'
export default {
  name: 'App',
  components: {
    Page,
    New
  },
  beforeCreate () {
    console.log('父元件App -------> App beforeCreate')
  },
  created () {
    console.log('父元件App -------> App created')
  },
  mounted () {
    console.log(
 
'父元件App -------> App mounted')
  },
  beforeMount () {
    console.log('父元件App -------> App beforeMount')
  }
}
</script>
</script>
 

New.vue

<template>
    <div>
        <p>this is a new component</p>
    </div>
</template>
 
<script>
export 
 
default {
    name: 'new',
  created () {
    console.log('子元件new ----> new created')
  },
  beforeCreate () {
    console.log('子元件new ----> new beforeCreate')
  },
  mounted () {
    console.log('子元件new ----> new mounted')
  },
  beforeMount () {
    console.log('子元件new ----> new beforeMount')
  }
}
</script>

Page.vue

<template>
    <div>
        <Job />
        <p>this is a page component</p>
    </div>
</template>
 
<script>
import Job from '@/components/job'
export default {
    name: 'page',
    components: {
        Job,
    },
    beforeCreate () {
        console.log('子元件page ----> page beforeCreate')
    },
    created () {
        console.log('子元件page ----> page created')
    },
    mounted () {
        console.log('子元件page ----> page mounted')
    },
    beforeMount () {
        console.log('子元件page ----> page beforeMount')
    }
}
</script>

<template>
    <div>
        <p>this is a job component, in page.vue</p>
    </div>
</template>
 
<script>
export default {
    name: 'job',
  created () {
    console.log('孫元件job ------> job created')
  },
  beforeCreate () {
    console.log('孫元件job ------> job beforeCreate')
  },
  mounted () {
    console.log('孫元件job ------> job mounted')
  },
  beforeMount () {
    console.log('孫元件job ------> job beforeMount')
  }
}
</script>

非同步引入時生命週期順序：父元件的beforeCreate、created、beforeMount、mounted --> 子元件的beforeCreate、created、beforeMount、mounted，示例略