按需引入elementUI步骤

1、安装elementUI

npm i element-ui -s

2、安装babel-plugin-component

npm install babel-plugin-component -D

3、修改babel.config.js

修改前

module.exports = {
  presets: [
    '@vue/cli-plugin-babel/preset'
  ]
}

 修改后

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

 4、在main.js中引入部分组件（比如Button和Select）

import Vue from 'vue';
import { Button, Select } from 'element-ui';
import App from './App.vue';

Vue.component(Button.name, Button);
Vue.component(Select.name, Select);

/* 或写为
 * Vue.use(Button)
 * Vue.use(Select)
 */

new Vue({
  el: '#app',
  render: h => h(App)
});