Vue2进阶之Vue3高级用法

Vue3高级用法

响应式
- Vue2：Object.defineProperty
- - Object.defineProperty
  - [this. $set设置响应式](#this.$ set设置响应式)
- Vue3：Proxy
[composition API](#composition API)
- [Vue2 option API和Vue3 compositionAPI](#Vue2 option API和Vue3 compositionAPI)
- reactive和shallowReactive
- readonly效果
- toRefs效果
生命周期
异步组件元素节点
- 正常写
- index.html
- main.js
- Async.vue
- AsyncComp.vue
- 使用异步
- - main.js
[teleport 传送门---createPortal React](#teleport 传送门—createPortal React)
自定义hooks

作业：Vue3官网所有内容过一遍 Vue3

响应式

Vue2：Object.defineProperty
Vue3：Proxy

Vue2：Object.defineProperty

Object.defineProperty

javascript 复制代码

//Vue2：Object.defineProperty

const initData={
  value:1
}

const data={}

Object.keys(initData).forEach(key=>{
  Object.defineProperty(data,key,{
    // getter setter
    get(){
      console.log("访问",key)
      return initData[key]
    },
    set(val){
      console.log("设置值",key)
      initData[key]=val
    }
  })
})

this.$set设置响应式

set给目的对象添加响应式属性后，并触发事件更新

this.$set(data,a,1)

Vue3：Proxy

javascript 复制代码

// Vue3：Proxy
const person={
  name:"张三"
}

let proxy=new Proxy(
  person,
  {
    get:function(target,key){
      if(key in target){
        return target[key]
      }
      throw new Error(`${key} is not defined`)
    },
    set(target,key,val){
      console.log("设置值",key)
      target[key]=val
    }
  }
)
let obj=Object.create(proxy)

proxy的正规写法：

javascript 复制代码

// Proxy正规写法
const initData={
  value:1
}
let proxy=new Proxy(
  initData,
  {
    get:function(target,key,receiver){
      console.log("访问",key)
      return Reflect.get(target,key,receiver)
    },
    set:function(target,key,val,receiver){
      console.log("修改",key)
      return Reflect.set(target,key,val,receiver)
    }
  }
)

拓展

怎么将esNext转换为es5写法？

通过babel，国外主流的swc转换

composition API

Vue2 option API和Vue3 compositionAPI

Vue3的compositionAPI和Vue2的optionsAPI的最大的区别是：更加倾向于函数式编程以及Vue3支持多个根节点

Vue2:

html 复制代码

<template>
   <!--XXXX-->
</template>
<script>
  export default {
     data(){
       return{ XXXX }
     },
     methods:{},
     computed:{}
  }
</script>
<style></style>

Vue2最容易产生的问题是：写一个文件一开始还好，写着写着就发现这个文件内容非常非常多，非常非常繁琐。

OptionAPI非常非常容易导致一个文件内容非常非常多，越往后越难改，非常非常容易出bug

Rect相对于Vue不容易写出那么夸张的效果

Vue2的mixin将组件单一内容拆解到一个文件，太灵活了，对多人协作不友好

=>Vue3主要解决的就是这个问题，将明确的逻辑抽象到一起

React=>自定义hook，将一部分的逻辑功能放到单一组件里去维护

App.vue

html 复制代码

<template>
  <div class="mine"></div>
</template>

<script>
import {defineComponent,ref,isRef} from 'vue'
export default defineComponent({
  // 相当于Vue2生命周期中的beforeCreate,created
  setup(){
    const count=ref(10)
    const user="张三"

    console.log("count,user",count,count.value,user)
    console.log("count is ref?",isRef(count))
    console.log("user is ref?",isRef(user))
  }
})
</script>

reactive和shallowReactive

html 复制代码

<template>
  <div class="mine"></div>
</template>

<script>
import {defineComponent,reactive,shallowReactive} from 'vue'
export default defineComponent({
  // 相当于Vue2生命周期中的beforeCreate,created
  setup(){
    const person={
      name:"张三",
      age:18,
      contacts:{
        phone:12345
      }
    }

    const personReactive=reactive(person)
    console.log("person reactive",personReactive)
    console.log("person reactive name",personReactive.name)
    console.log("person reactive contacts",personReactive.contacts)

    console.log("--------------分割线------------------------")

    const shallowPersonReactive=shallowReactive(person)
    console.log("shallow person reactive",shallowPersonReactive)
    console.log("shallow person reactive name",shallowPersonReactive.name)
    console.log("shallow person reactive contacts",shallowPersonReactive.contacts)

    
  }
})
</script>

readonly效果

html 复制代码

<template>
  <div class="mine"></div>
</template>

<script>
import {defineComponent,ref,reactive,readonly} from 'vue'
export default defineComponent({
  // 相当于Vue2生命周期中的beforeCreate,created
  setup(){
    const count=ref(10)
    const obj=reactive({
      abc:18,
      count,
      userInfo:{
        age:66
      }
    })

    console.log("reactive obj:",obj)
    // 在Proxy的set中，是不允许做修改的
    const objOnly=readonly(obj)  

    console.log("readonly obj:",objOnly)
    objOnly.abc=100
    console.log("readonly obj:",objOnly)
    
  }
})
</script>

toRefs效果

html 复制代码

<template>
  <div class="mine"></div>
</template>

<script>
import {defineComponent,ref,isRef,reactive,shallowReactive,readonly, toRefs} from 'vue'
export default defineComponent({
  // 相当于Vue2生命周期中的beforeCreate,created
  setup(){
    const count=ref(10)
    const obj=reactive({
      abc:18,
      count,
      userInfo:{
        age:66
      }
    })

    console.log("reactive obj:",obj)

    console.log("toRefs obj",toRefs(obj))
    
  }
})
</script>

如果是通过ref创建出来的，一般是RefImpl，如果是通过toRefs创建出来的，一般把toRefs视为一个对象，针对对象里的所有属性，全部转换为toRefs的效果

生命周期

经常应用的场景：

1.初始化 mount

2.数据变化 update

3.卸载 unmount

加入LiftCycle组件

main.js

javascript 复制代码

import { createApp } from 'vue'
import App from './App.vue'

import LifeCycle from './LifeCycle.vue'

createApp(App).mount('#app')

createApp(LifeCycle).mount('#lifeCycle')

index.html

html 复制代码

<div id="lifeCycle"></div>

全部：

html 复制代码

<!DOCTYPE html>
<html lang="">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
    <title><%= htmlWebpackPlugin.options.title %></title>
  </head>
  <body>
    <noscript>
      <strong>We're sorry but <%= htmlWebpackPlugin.options.title %> doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
    </noscript>
    <div id="app"></div>
    <!-- built files will be auto injected -->
     <div id="lifeCycle"></div>
  </body>
</html>

LifeCycle.vue

html 复制代码

<template>
    <div>
      {{ count }}
      {{ name }}
    </div>
    <button @click="addNumber">+1</button>
    <button @click="updateName">update name</button>
</template>
<script>
export default {
   data() {
      return {
        count:0,
        name:"张三"
      }
   },
   methods:{
    addNumber(){
      this.count++
    },
    updateName(){
      this.name = "李四"
    }
   },
  //  1.初始化，data还不能用
   beforeCreate(){
    console.log("beforeCreate")
   },
  //   data可以用,dom不可用
   created(){
    console.log("created")
   },
  //   挂载之前，DOM还没有生成
   beforeMount(){
    console.log("beforeMount")
   },
  //   在VNode(初次渲染/更新)渲染时调用
   renderTracked({key,target,type}){
    console.log("renderTracked",key,target,type)
   },
  //  挂载之后，DOM已经生成
   mounted(){
    console.log("mounted")
    console.log("-------------------------------------------------------------")
   },
   

   //  2.update
  renderTriggered({key,target,type}){
    console.log("renderTriggered",key,target,type)
  },
  beforeUpdate(){
    console.log("beforeUpdate")
  },
  renderTracked({key,target,type}){
    console.log("renderTriggered",key,target,type)
  },
  updated(){
    console.log("updated")
  },

  // 3.卸载
  beforeUnmount(){
    console.log("beforeUnmount")
  },
  unmounted(){
    console.log("unmounted")
  }
}
</script>
<style scoped>

</style>

异步组件元素节点

正常写

src
- Async.vue
- components
  - AsyncComp.vue

index.html

html 复制代码

<!-- 3.异步组件元素节点 -->
<div id="async"></div>

html 复制代码

<!DOCTYPE html>
<html lang="">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
    <title><%= htmlWebpackPlugin.options.title %></title>
  </head>
  <body>
    <noscript>
      <strong>We're sorry but <%= htmlWebpackPlugin.options.title %> doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
    </noscript>
    <!-- 1.composition 元素节点 -->
    <div id="app"></div>
    <!-- built files will be auto injected -->
     <!-- 2.生命周期元素节点 -->
     <div id="lifeCycle"></div>
     <!-- 3.异步组件元素节点 -->
      <div id="async"></div>
  </body>
</html>

main.js

javascript 复制代码

import { createApp } from 'vue'
import App from './App.vue'

import LifeCycle from './LifeCycle.vue'

import Async from './Async.vue'
import AsyncComp from './components/AsyncComp.vue'

createApp(App).mount('#app')

createApp(LifeCycle).mount('#lifeCycle')

const async=createApp(Async)
async.component("async-comp",AsyncComp)
async.mount('#async')

Async.vue

html 复制代码

<template>
  ASYNC
  <async-comp></async-comp>
</template>

<script setup lang="ts">

</script>

<style scoped>

</style>

AsyncComp.vue

html 复制代码

<template>
  <div>async defineComponent</div>
</template>

<script setup lang="ts">

</script>

<style scoped>

</style>

但是这样执行

pnpm run build

打包后，只会生成一个js文件

使用异步

main.js

javascript 复制代码

const AsyncComp=defineAsyncComponent(()=>import('./components/AsyncComp.vue'))

async.component("async-comp",AsyncComp)

全部代码：

javascript 复制代码

import { createApp,defineAsyncComponent } from 'vue'
import App from './App.vue'

import LifeCycle from './LifeCycle.vue'

import Async from './Async.vue'
// import AsyncComp from './components/AsyncComp.vue'

createApp(App).mount('#app')

createApp(LifeCycle).mount('#lifeCycle')

const async=createApp(Async)

const AsyncComp=defineAsyncComponent(()=>import('./components/AsyncComp.vue'))

async.component("async-comp",AsyncComp)
async.mount('#async')

再执行

pnpm run build

会生成两个js文件

这两个文件是将我们异步的组件给单独拿出来，将异步组件单独拿出来的效果是，因为要做的是异步组件的动态引入，一般是额外使用或之后去用，就没有必要跟原先代码单独一起打包。

对应的是React.lazy和React中的suspense

js 复制代码

const myComponent=React.lazy(()=>import('./Component'))

function MyComponent(){
    return (
        <div>
            <Suspense fallback={<Loading />}>
              <Component />
            </Suspense>
        </div>
    )
}

teleport 传送门---createPortal React

将子节点渲染到父节点以外的DOM的方式

src
Dialog.vue

index.html

html 复制代码

<!-- 4.teleport 元素节点 -->
<div id="dialog"></div>

全部代码：

html 复制代码

<!DOCTYPE html>
<html lang="">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
    <title><%= htmlWebpackPlugin.options.title %></title>
  </head>
  <body>
    <noscript>
      <strong>We're sorry but <%= htmlWebpackPlugin.options.title %> doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
    </noscript>
    <!-- 1.composition 元素节点 -->
    <div id="app"></div>
    <!-- built files will be auto injected -->
     <!-- 2.生命周期元素节点 -->
     <div id="lifeCycle"></div>
     <!-- 3.异步组件元素节点 -->
      <div id="async"></div>
      <!-- 4.teleport 元素节点 -->
       <div id="dialog"></div>
  </body>
</html>

main.js

javascript 复制代码

const dialog=createApp(Dialog)
dialog.mount('#dialog')

全部代码：

javascript 复制代码

import { createApp,defineAsyncComponent } from 'vue'
import App from './App.vue'

import LifeCycle from './LifeCycle.vue'

import Async from './Async.vue'
import Dialog from './Dialog.vue'
// import AsyncComp from './components/AsyncComp.vue'

createApp(App).mount('#app')

createApp(LifeCycle).mount('#lifeCycle')

const async=createApp(Async)

const AsyncComp=defineAsyncComponent(()=>import('./components/AsyncComp.vue'))

async.component("async-comp",AsyncComp)
async.mount('#async')

const dialog=createApp(Dialog)
dialog.mount('#dialog')

Dialog.vue

html 复制代码

<template>
  <div class="portals">
    <button @click="showNotification">切换弹窗</button>
    <teleport to="#dialog">
      <div v-if="isOpen" class="notification">
        这是一个弹窗
      </div>
    </teleport>
  </div>
</template>
<script>
import { ref } from 'vue';

export default {
    setup(){
        const isOpen=ref(false)
        let closePopup
        const showNotification=()=>{
            isOpen.value=true

            clearTimeout(closePopup)

            closePopup=setTimeout(()=>{
                isOpen.value=false
            },20000)
        }

        return {
            isOpen,
            showNotification
        }
    }
}
</script>
<style scoped>
.notification{
    position: fixed;
    bottom: 20px;
    background-color: #fff;
    border: 1px solid #ccc;
    width: 300px;
    padding:30px;
}
</style>

弹窗是挂载在dialog下的，而不是protals下

自定义hooks

hooks最重要的特点：对于我们来说，不需要关心内部的逻辑，而且与Vue2相比，提供了一个非常合理的方式，使用Vue2的option API很容易写出三五千行的代码，但是对于函数式编程来说，按照逻辑功能拆分下来，一个文件至少包含一个功能，其他功能引用即可。

public
- index.html
src
- hooks
  - useMousePosition.js
- MouseMove.vue
- main.js

index.html

html 复制代码

<!-- 5.自定义hook -->
<div id="mousemove"></div>

全部代码：

html 复制代码

<!DOCTYPE html>
<html lang="">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
    <title><%= htmlWebpackPlugin.options.title %></title>
  </head>
  <body>
    <noscript>
      <strong>We're sorry but <%= htmlWebpackPlugin.options.title %> doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
    </noscript>
    <!-- 1.composition 元素节点 -->
    <div id="app"></div>
    <!-- built files will be auto injected -->
    <!-- 2.生命周期元素节点 -->
    <div id="lifeCycle"></div>
    <!-- 3.异步组件元素节点 -->
    <div id="async"></div>
    <!-- 4.teleport 元素节点 -->
    <div id="dialog"></div>
    <!-- 5.自定义hook -->
    <div id="mousemove"></div>
  </body>
</html>

main.js

javascript 复制代码

import MouseMove from './MouseMove.vue'

const mousemove=createApp(MouseMove)
mousemove.mount('#mousemove')

全部代码：

javascript 复制代码

import { createApp,defineAsyncComponent } from 'vue'
import App from './App.vue'

import LifeCycle from './LifeCycle.vue'

import Async from './Async.vue'
import Dialog from './Dialog.vue'
// import AsyncComp from './components/AsyncComp.vue'
import MouseMove from './MouseMove.vue'


// createApp(App).mount('#app')

// createApp(LifeCycle).mount('#lifeCycle')

// const async=createApp(Async)

// const AsyncComp=defineAsyncComponent(()=>import('./components/AsyncComp.vue'))

// async.component("async-comp",AsyncComp)
// async.mount('#async')

// const dialog=createApp(Dialog)
// dialog.mount('#dialog')

const mousemove=createApp(MouseMove)
mousemove.mount('#mousemove')

useMousePosition.js

javascript 复制代码

import { onMounted, onUnmounted, ref } from "vue";

function useMousePosition() {
  const x=ref(0)
  const y=ref(0)


  const updateMouse=e=>{
    x.value=e.pageX
    y.value=e.pageY
  }

  onMounted(()=>{
    document.addEventListener('click',updateMouse)
  }) 

  onUnmounted(()=>{
    document.removeEventListener('click',updateMouse)
  })

  return{
    x,
    y
  }
}

export default useMousePosition

MouseMove.vue

html 复制代码

<!-- 提供鼠标位置自定义hooks -->
<template>
  <div>
    <p>X：{{x}}</p>
    <p>Y：{{y}}</p>
  </div>
</template>

<script>
import { defineComponent } from 'vue';
import useMousePosition from './hooks/useMousePosition';

export default defineComponent({
  setup(){
    const {x,y}=useMousePosition()
    return {
      x,y
    }
  }
})
</script>

<style scoped>

</style>