一文搞懂Vue3中的异步组件defineAsyncComponentAPI的用法

<template>
  <logo-img />
  <hello-world msg="Welcome to Your Vue.js App" />
</template>

<script setup>
import LogoImg from './components/LogoImg.vue'
import HelloWorld from './components/HelloWorld.vue'
</script>

<template>
  <logo-img />
  <hello-world msg="Welcome to Your Vue.js App" />
</template>

<script setup>
import { defineAsyncComponent } from 'vue'
import LogoImg from './components/LogoImg.vue'

// 简单用法
const HelloWorld = defineAsyncComponent(() =>
  import('./components/HelloWorld.vue'),
)
</script>

<script setup>
import { defineAsyncComponent } from 'vue'
import LogoImg from './components/LogoImg.vue'

// 定义一个耗时执行的函数，t 表示延迟的时间， callback 表示需要执行的函数，可选
const time = (t, callback = () => {}) => {
  return new Promise(resolve => {
    setTimeout(() => {
      callback()
      resolve()
    }, t)
  })
}
// 定义异步组件，这里这样写是为了查看效果
const HelloWorld = defineAsyncComponent(() => {
  return new Promise((resolve, reject) => {
    ;(async function () {
      try {
        await time(2000)
        const res = await import('./components/HelloWorld.vue')
        resolve(res)
      } catch (error) {
        reject(error)
      }
    })()
  })
})
</script>

<template>
  <logo-img />
  <hello-world msg="Welcome to Your Vue.js App" />
</template>
<script setup>
import { defineAsyncComponent } from 'vue'
import LogoImg from './components/LogoImg.vue'
import LoadingComponent from './components/loading.vue'
import ErrorComponent from './components/error.vue'

// 定义一个耗时执行的函数，t 表示延迟的时间， callback 表示需要执行的函数，可选
const time = (t, callback = () => {}) => {
  return new Promise(resolve => {
    setTimeout(() => {
      callback()
      resolve()
    }, t)
  })
}
// 记录加载次数
let count = 0
const HelloWorld = defineAsyncComponent({
  // 工厂函数
  loader: () => {
    return new Promise((resolve, reject) => {
      ;(async function () {
        await time(300)
        const res = await import('./components/HelloWorld.vue')
        if (++count < 3) {
          // 前两次加载手动设置加载失败
          reject(res)
        } else {
          // 大于3次成功
          resolve(res)
        }
      })()
    })
  },
  loadingComponent: LoadingComponent,
  errorComponent: ErrorComponent,
  delay: 0,
  timeout: 1000,
  suspensible: false,
  onError(error, retry, fail, attempts) {
    // 注意，retry/fail 就像 promise 的 resolve/reject 一样：
    // 必须调用其中一个才能继续错误处理。
    if (attempts < 3) {
      // 请求发生错误时重试，最多可尝试 3 次
      console.log(attempts)
      retry()
    } else {
      fail()
    }
  },
})
</script>