配置babel.config.js

```module.exports = {
      presets: [
            '@vue/cli-plugin-babel/preset'
      ],plugins: [
        [
          "component",
          {
            libraryName: "element-ui",
            styleLibraryName: "theme-chalk"
          }
        ]
      ]
    }
```

注意！不能把官网的"presets": [["es2015", { "modules": false }]]加上去

需要使用element组件的组件中按需引入

        ```import Vue from "vue";
           import { Upload } from "element-ui";
           Vue.use(Upload);
        ```