關於vue元件的引入方式有兩種

一、 同步引入

例子： import Page from '@/components/page'

二、非同步引入

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

兩種引入方式的不同之處在於：

同步引入時生命週期順序為：父元件的beforeMount、created、beforeMount --> 所有子元件的beforeMount、created、beforeMount --> 所有子元件的mounted

<! -- 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>

<!-- job.vue -->
<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 在上面的程式碼只需要修改引入的方式：

import Page from '@/components/page' // 同步方式引入
import New from '@/components/new'

import Job from '@/components/job'

改為：

const Page = () => import ('@/components/page')  // 非同步引入
const New = () => import ('@components/new')

const Job = () => import ('@/components/job'

結果：