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1.如果自己电脑vue版本是vue2版本，下面将详细介绍如何在vue2版本基础上继续安装
vue3版本且不会影响vue2版本的使用

    1-1 在c盘或者别的盘建一个文件夹vue3

    1-2 在这个文件夹里使用WIN+R 打开终端 输入命令 npm install @vue/cli 安装完即可

    1-3 然后进入此文件夹中的node_modules中的.bin文件夹中，修改里面文件如下：

     vue修改为vue3,  vue.cmd修改为vue3.cmd   

   1-4 然后把vue3.cmd拖拽到命令窗口中加上-v即可看到版本号 如下图所示

    1-5 接下来就是配置环境变量

        1-5-1 打开电脑系统属性-高级-环境变量

         

     1-5-2  点击系统变量下方的新建 配置新的变量  

        变量名：vue3_cli  变量值："C:\vue3\node_modules\.bin"(根据自己位置就行)

               1-5-3 点击变量中的path  点击编辑 完了把新增 把%vue_cli3%

    1-5-5 如果是建vue3项目的话 具体命令是 vue3 create demo_project,然后根据具体内容去选择

2.element-plus新增组件库

  2-1 Text 基本用法 具体代码如下(可以直接新建完项目以后粘贴验证)：

<template><div class="div_container"><h3>Text 基本用法</h3><el-text class="mr-5">Default</el-text><el-text class="mr-5" type="primary">Primary</el-text><el-text class="mr-5" type="success">Success</el-text><el-text class="mr-5" type="info">Info</el-text><el-text class="mr-5" type="warning">Warning</el-text><el-text class="mr-5" type="danger">Danger</el-text><h3>Text 尺寸</h3><el-text class="mr-5" size="large">Large</el-text><el-text class="mr-5">Default</el-text><el-text class="mr-5" size="small">Small</el-text><h3 style="margin-bottom: 10px">Text 省略</h3><div style="margin-bottom: 10px">通过 truncated 属性，在文本超过视图或最大宽度设置时展示省略符。 通过line-clamp 属性控制多行的样式</div><div><el-text class="w-150px mb-2" truncated>Self element set width 100px</el-text><el-row class="w-150px mb-2"><el-text truncated>Squeezed by parent element</el-text></el-row><el-text line-clamp="2">The -webkit-line-clamp CSS property<br />allows limiting of the contents of<br />a block to the specified number of lines.</el-text></div><h3>Text 覆盖</h3><el-space direction="vertical"><el-text>span</el-text><el-text tag="p">This is a paragraph.</el-text><el-text tag="b">Bold</el-text><el-text tag="i">Italic</el-text><el-text>This is<el-text tag="sub" size="small">subscript</el-text></el-text><el-text>This is<el-text tag="sup" size="small">superscript</el-text></el-text><el-text tag="ins">Inserted</el-text><el-text tag="del">Deleted</el-text><el-text tag="mark">Marked</el-text></el-space></div>
</template><script setup>
import "@element-plus/icons-vue";
</script>
<style scoped>
.div_container {
}
.mr-5 {margin-right: 5px;
}
.w-150px {width: 150px;
}
.mb-2 {margin-bottom: 2px;
}
</style>

        2-2 TreeSelect 树形选择

<template><h3>TreeSelect 树形选择 选择任意级别</h3><div style="color: lightseagreen">(注意：当属性 check-strictly=true时，任何节点都可以被选择，否则只有子节点可被选择。)</div><div class="node_css mt_15"><el-tree-selectv-model="value":data="data":check-strictly="checkStrictly":render-after-expand="false"style="width: 240px"/><div class="mt_15">show checkbox(only click checkbox to select):<el-tree-selectv-model="value2":data="data":check-strictly="checkStrictly":render-after-expand="false"show-checkboxstyle="width: 240px"/></div><div class="mt_15">show checkbox with `check-on-click-node`:<el-tree-selectv-model="value3":data="data":check-strictly="checkStrictly":render-after-expand="false"show-checkboxcheck-on-click-nodestyle="width: 240px"/></div></div><div style="display: flex; flex-direction: row"><div style="flex: 5"><el-watermark:width="130":height="30"image="https://element-plus.org/images/element-plus-logo.svg"><div style="height: 500px" /></el-watermark></div><div style="flex: 5"><el-watermark:font="font":content="['Element+', 'Element Plus']":width="130":height="40"><div style="height: 500px" /></el-watermark></div></div>
</template><script setup>
import { ref, reactive, toRaw, onMounted } from "vue";
const value = ref();
const value2 = ref();
const value3 = ref();
const checkStrictly = ref(false);
const demolist = reactive({list: [{title: "一般",// icon: h(Home),name: "home",value: "0",},{title: "还好",// icon: h(Category),name: "category",value: "0",},{title: "很好",// icon: h(Find),name: "find",value: "0",},{title: "最爱",// icon: h(Cart),name: "cart",value: "0",},{title: "改进",// icon: h(My),name: "my",value: "0",},],
});
const data = [{value: "1",label: "Level one 1",children: [{value: "1-1",label: "Level two 1-1",children: [{value: "1-1-1",label: "Level three 1-1-1",},],},],},{value: "2",label: "Level one 2",children: [{value: "2-1",label: "Level two 2-1",children: [{value: "2-1-1",label: "Level three 2-1-1",},],},{value: "2-2",label: "Level two 2-2",children: [{value: "2-2-1",label: "Level three 2-2-1",},],},],},{value: "3",label: "Level one 3",children: [{value: "3-1",label: "Level two 3-1",children: [{value: "3-1-1",label: "Level three 3-1-1",},],},{value: "3-2",label: "Level two 3-2",children: [{value: "3-2-1",label: "Level three 3-2-1",},],},],},
];
onMounted(() => {console.log(demolist, "demolist");console.log(toRaw(demolist));// console.log(JSON.parse(JSON.stringify(demolist)));
});
</script>
<style scoped>
.mt_15 {margin-top: 15px;
}
.node_css {display: flex;flex-direction: column;
}
</style>

3.vue3新增属性-setup使用俩种方式

    3-1 第一种方式  标签以外写 setup 函数，需要显式导入 defineComponent，但上下文指向组件实例，可以使用传统的生命周期钩子和直接访问组件的属性和方法。

    3-2 第二种方式  语法更简洁，但上下文不指向组件实例。

<script setup>import {onMounted, ref} from 'vue';const value=ref();const showFlag=ref(false);const handleClick=()=>{};onMounted(()=>{ console.log(showFlag)})
</script>

4.vue3已废除$set向对象中添加响应式的属性 以下是常用的集中方法

     4-1  使用ES6属性 Reflect

<script setup>import { ref, reactive, toRaw, onMounted } from "vue";const demolist = reactive({list: [{title: "一般",// icon: h(Home),name: "home",value: "0",},{title: "还好",// icon: h(Category),name: "category",value: "0",},{title: "很好",// icon: h(Find),name: "find",value: "0",},{title: "最爱",// icon: h(Cart),name: "cart",value: "0",},{title: "改进",// icon: h(My),name: "my",value: "0",},],});   const inpChange = () => {for (var e = 0; e < toRaw(demolist.list).length; e++) {Reflect.set(toRaw(demolist.list)[e], "index", e + 1);}console.log(toRaw(demolist), "demolist");}
</script>

   4-2  使用vue3响应式

<script setup>import { ref, reactive, toRaw, onMounted } from "vue";const demolist = reactive({list: [{title: "一般",// icon: h(Home),name: "home",value: "0",},{title: "还好",// icon: h(Category),name: "category",value: "0",},{title: "很好",// icon: h(Find),name: "find",value: "0",},{title: "最爱",// icon: h(Cart),name: "cart",value: "0",},{title: "改进",// icon: h(My),name: "my",value: "0",},],});   const inpChange = () => {for (var e = 0; e < toRaw(demolist.list).length; e++) {toRaw(demolist.list)[e].index = e + 1;}console.log(toRaw(demolist), "demolist");}
</script>

效果图如下：

 

   4-3 上述俩种是有一定规律添加 如果是特定的添加 用以下这种方法

<script setup>import { ref, reactive, toRaw, onMounted } from "vue";const demolist = reactive({list: [{title: "一般",// icon: h(Home),name: "home",value: "0",},{title: "还好",// icon: h(Category),name: "category",value: "0",},{title: "很好",// icon: h(Find),name: "find",value: "0",},{title: "最爱",// icon: h(Cart),name: "cart",value: "0",},{title: "改进",// icon: h(My),name: "my",value: "0",},],});   const inpChange = () => {for (var e = 0; e < toRaw(demolist.list).length; e++) {if (e % 2 == 0) {console.log(toRaw(demolist.list[e]),"toRaw(demolist.list[e] %2===0";toRaw(demolist.list)[e].index = e + 1;} else {console.log(toRaw(demolist.list[e]),"toRaw(demolist.list[e] %2!==0");toRaw(demolist.list)[e].index = e + 2;}}console.log(toRaw(demolist), "demolist");}
</script>

效果图如下：

  4-4 vue3写法归总 持续更新中......

1.获取输入框 下拉框的值  使用.value去拿2.但是如果你这个属性是还包了一层 reactive 那么你就这样就代理了 打印出的值是包在了Proxy里想要获取值有俩种方式:第一种是vue自带的 toRaw(objectTarget) 第二种是序列化使用 JSON.parse(JSON.stringfy(objectTarget))

5.vue3七种传值方式

   5-1 Props方式

父组件代码
<template><child-components :list="list"></child-components><div><input v-model="value" type="text" placeholder="请输入"/><button @click="handleAdd" type="button">添加</button></div>
</template>
<script setup>
import { ref } from 'vue'
import ChildComponents from './child.vue'
const list = ref(['JavaScript', 'HTML', 'CSS'])
const value= ref('')
// add 触发后的事件处理函数
const handleAdd = () => list.value.push(value.value)
</script>子组件代码(子组件只需要对父组件传递的值进行渲染即可)
<template><ul ><li v-for="i in props.list" :key="i">{{ i }}</li></ul>
</template>
<script setup>
import { defineProps } from 'vue'
const props = defineProps({list: {type: Array,default: () => [],},
})
</script>

效果图如下：

 

   5-2 emit方式 (emit方式也是Vue中最常见的组件通信方式，该方式用于子传父) 效果图如上所述     就不展示了

父组件 在父组件中只需要监听子组件自定义的事件，然后执行对应的添加操作。
<template><h8>我是父组件</h8><ul><li v-for="i in list" :key="i">{{ i }}</li></ul><child-components @add="handleAdd"></child-components>
</template>
<script setup>
import { ref } from "vue";
import ChildComponents from "./MainPage.vue";
const list = ref(["JavaScript", "HTML", "CSS"]);
// add 触发后的事件处理函数
const handleAdd = (value) => {list.value.push(value);
};
</script>子组件 在子组件中点击【添加】按钮后，emit一个自定义事件，并将添加的值作为参数传递。
<template><h8>我是子组件</h8><div><input v-model="value" type="text" placeholder="请输入" /><button @click="handleSubmit" type="button">添加</button></div>
</template>
<script setup>
import { ref, defineEmits } from "vue";
const value = ref("");
const emits = defineEmits(["add"]);
const handleSubmit = () => {emits("add", value.value);value.value = "";
};
</script>

   5-3 v-model 是vue3 比较出色的语法糖 将会着重讲

       5-3-1 单独传值如下:

父组件
<template><h8>我是父组件</h8><ul><li v-for="i in list" :key="i">{{ i }}</li></ul><child-components v-model:list="list"></child-components>
</template>
<script setup>
import { ref } from "vue";
import ChildComponents from "./MainPage.vue";
const list = ref(["JavaScript", "HTML", "CSS"]);
</script>子组件
<template><h8>我是子组件</h8><div><input v-model="value" type="text" placeholder="请输入" /><button @click="handleAdd" type="button">添加</button></div>
</template>
<script setup>
import { ref, defineEmits, defineProps } from "vue";
const value = ref("");
const props = defineProps({list: {type: Array,default: () => [],},
});
const emits = defineEmits(["update:list"]);
// 添加操作
const handleAdd = () => {const arr = props.list;arr.push(value.value);emits("update:list", arr);value.value = "";
};
</script>

      5-3-2  多个传值情况写法如下：

      

特别需要注意俩点：1.在父组件中  绑俩个v-model<child-components v-model:list="list" v-model:listCopy='listCopy'></child-components>2.在子组件中  const emits = defineEmits(["update:list","update:listCopy"]);
父组件
<template><h4>我是父组件</h4><ul><li v-for="i in list" :key="i">{{ i }}</li></ul><h4>我是父组件Copy</h4><ul><li v-for="i in listCopy" :key="i">{{ i }}</li></ul><child-components v-model:list="list" v-model:listCopy='listCopy'></child-components>
</template>
<script setup>
import { ref } from "vue";
import ChildComponents from "./MainPage.vue";
const list = ref(["JavaScript", "HTML", "CSS"]);
const list = ref(["JavaScriptCopy", "HTMLCopy", "CSSCopy"]);
</script>子组件
<template><h4>我是子组件</h4><div><input v-model="value" type="text" placeholder="请输入" /><button @click="handleAdd" type="button">添加</button></div><h4>我是子组件Copy</h4><div><input v-model="valueCopy" type="text" placeholder="请输入" /><button @click="handleAddCopy" type="button">添加</button></div>
</template>
<script setup>
import { ref, defineEmits, defineProps } from "vue";
const value = ref("");
const valueCopy = ref("");
const props = defineProps({list: {type: Array,default: () => [],},listCopy: {type: Array,default: () => [],},
});
const emits = defineEmits(["update:list","update:listCopy"]);
// 添加操作
const handleAdd = () => {const arr = props.list;arr.push(value.value);emits("update:list", arr);value.value = "";
};
const handleAddCopy = () => {const arr = props.listCopy;arr.push(valueCopy.value);emits("update:listCopy", arr);valueCopy.value = "";
};
</script>

 

  5-4  refs 

在使用选项式API时，我们可以通过this.$refs.name的方式获取指定元素或者组件，但是组合式API中就无法使用哪种方式获取。如果我们想要通过ref的方式获取组件或者元素，需要定义一个同名的Ref对象，在组件挂载后就可以访问了。

父组件
<template><ul><li v-for="i in childRefs?.list" :key="i">{{ i }}</li></ul><!-- 子组件 ref的值与<script>中的保持一致 --><child-components ref="childRefs"></child-components><!-- 父组件 -->
</template>
<script setup>
import { ref } from 'vue'
import ChildComponents from './MainPage.vue'
const childRefs = ref(null)
</script>子组件
<template><div><input v-model="value" placeholder="请输入"/><button @click="handleAdd" type="button">添加</button></div>
</template>
<script setup>
import { ref, defineExpose } from 'vue'
const list = ref(['JavaScript', 'HTML', 'CSS'])
const value= ref('1')
// add触发后的事件处理函数
const handleAdd = () => {list.value.push(value.value)value.value = ''
}
defineExpose({ list })
</script>

   5-5 provide/inject 

   provide和inject是Vue中提供的一对API，该API可以实现父组件向子组件传递数据，无论层级有     多深，都可以通过这对API实现。示例代码如下所示：

父组件
<template><!-- 子组件 --><child-components></child-components><!-- 父组件 --><div><input v-model="value" placeholder="请输入"/><button @click="handleAdd" type="button">添加</button></div>
</template>
<script setup>
import { ref, provide } from 'vue'
import ChildComponents from './MainPage.vue'
const list = ref(['JavaScript', 'HTML', 'CSS'])
const value= ref('')
// 向子组件提供数据
provide('list', list.value)
// add 触发后的事件处理函数
const handleAdd = () => {list.value.push(value.value)value.value = ''
}
</script>子组件
<template><ul ><li v-for="i in list" :key="i">{{ i }}</li></ul>
</template>
<script setup>
import { inject } from 'vue'
// 接受父组件提供的数据
const list = inject('list')
</script>

   5-6 事件总线 结合外部第三方库来完成 官方推荐了俩种 mitt和tiny-emitter

   我这里以mitt为例来说

       5-6-1 首先安装mitt

npm install mitt

        5-6-2  找到vue项目中的utils文件夹，新建一个bus.js，代码：

import mitt from "mitt";
const mitter = mitt();
export default mitter;

        5-6-3 使用 我现在使用mitt进行兄弟组件之间的通信实现

父组件
<template><child1></child1> <child2></child2>
</template>
<script setup>import Child1 from "./MainPage.vue";import Child2 from "./GoodsPage.vue";
</script>

子组件-child1
<template><div>child1<button @click="click">给child2 传值</button></div>
</template>
<script setup>
import emitter from "@/utils/bus";function click() {emitter.emit("child2Data", { name: "小米" });}
</script>

子组件-child2
<template><div>child2---{{ str }}</div>
</template>
<script setup>
import emitter from "@/utils/bus";
import { onBeforeUnmount, ref } from "vue";
let str = ref();
emitter.on("child2Data", (data) => {str.value = data.name;
});
onBeforeUnmount(() => {emitter.off("child2Data"); //关闭
});
</script>

 效果图如下：

6.后续会陆续补充：

   6-1 创建vue3项目的时候一些选择

   6-2 element-plus新增组件在实际项目中使用

   6-3 vue3新增属性及生命周期及写法+element-plus 在实际项目中使用

持续更新中......