unresolved compilation problem:（完美解决 Compiled with problems: × ERROR Cannot read properties of undefined (readin）

启动vue ui 使用npm  run  serve编译启动时 , 出现以下问题:

Compiled with problems:

x

ERROR

Cannot read properties of undefined (reading use) TypeError: Cannot read properties of undefined (reading use) at eval (webpack-internal:///./src/plugins/element.js:13:45) at ./src/plugins/element.js (http://localhost:8080/js/app.js:96:1) at webpack_require (http://localhost:8080/js/app.js:337:33) at fn (http://localhost:8080/js/app.js:592:21) at eval (webpack-internal:///./src/main.js:5:77) at ./src/main.js (http://localhost:8080/js/app.js:85:1) at webpack_require (http://localhost:8080/js/app.js:337:33) at http://localhost:8080/js/app.js:1517:109 at webpack_require.O (http://localhost:8080/js/app.js:383:23) at http://localhost:8080/js/app.js:1518:53

错误截图如下:

 解决方法: 

1. 重新创建一个新项目

2. 重新安装依赖. 出现这个问题我是因为我的依赖没有安装好

npm install -g vue 安装全局vue

npm install -g @vue/cli 安装vue脚手架  
    
    
    ，加一个@是最新的版本

3. 修改main.js里面代码   导入包的方式不对

import { createApp } from vue import App from ./App.vue import router from ./router/index const app = createApp(App) app.use(router).mount(#app)

定义一个变量去存,使用变量去调用