在我学习Vue路线上，ElementUI的使用属于很大的一部分，但是在我第一次引入ElementUI，编译的时候，便是出现的如下的问题

Compiling... WAIT                                                                                          3:16:50 ├F10: PM┤
98% after emitting CopyPlugin

ERROR  Failed to compile with 1 errors                                                                      3:16:52 ├F10: PM┤
ERROR  in ./src/main.js

Module Error (from ./node_modules/eslint-loader/index.js):

C:\****\******\*****\****-vue\hello-world\src\main.js
  2:8  error  'ElementUI' is defined but never used  no-unused-vars

✖ 1 problem (1 error, 0 warnings)


 @ multi (webpack)-dev-server/client?http://192.168.1.104:8080&sockPath=/sockjs-node (webpack)/hot/dev-server.js ./src/main.js

这时我的package.json是这个样子的

{
  "name": "hello-world",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "core-js": "^3.6.5",
    "element-ui": "^2.13.2",
    "vue": "^2.6.11"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "~4.4.0",
    "@vue/cli-plugin-eslint": "~4.4.0",
    "@vue/cli-service": "~4.4.0",
    "babel-eslint": "^10.1.0",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^6.2.2",
    "less-loader": "^6.2.0",
    "vue-template-compiler": "^2.6.11"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "parserOptions": {
      "parser": "babel-eslint"
    },
    "rules": {
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not dead"
  ]
}

其原因呢，是因为该项目安装了eslint规范，ESLint 是在 ECMAScript/JavaScript 代码中识别和报告模式匹配的工具，它的目标是保证代码的一致性和避免错误。在许多方面，它和 JSLint、JSHint 相似。

所以我们要对package.json稍稍做点修改，修改过后如下

{
  "name": "hello-world",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "core-js": "^3.6.5",
    "element-ui": "^2.13.2",
    "vue": "^2.6.11"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "~4.4.0",
    "@vue/cli-plugin-eslint": "~4.4.0",
    "@vue/cli-service": "~4.4.0",
    "babel-eslint": "^10.1.0",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^6.2.2",
    "less-loader": "^6.2.0",
    "vue-template-compiler": "^2.6.11"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "parserOptions": {
      "parser": "babel-eslint"
    },
    "rules": {
      "generator-star-spacing": "off",
      "no-tabs": "off",
      "no-unused-vars": "off",
      "no-console": "off",
      "no-irregular-whitespace": "off",
      "no-debugger": "off"
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not dead"
  ]
}