CentOs8にEslintの導入手順

## 検証ディレクトリ作成
mkdir eslint

## 移動
cd eslint

## 全てyesなので
npm init -y

## インストール
npm i -D eslint

<出力結果>
npm ERR! code ENOSELF
npm ERR! Refusing to install package with name "eslint" under a package
npm ERR! also called "eslint". Did you name your project the same
npm ERR! as the dependency you're installing?
npm ERR! 
npm ERR! For more information, see:
npm ERR!     <https://docs.npmjs.com/cli/install#limitations-of-npms-install-algorithm>

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/testuser/.npm/_logs/2019-10-29T08_28_16_492Z-debug.lo

"name": "eslint",
↓
"name": "",

## インストール
npm i -D eslint

## バージョン確認
eslint -v

<出力結果>
bash: eslint: コマンドが見つかりませんでした...

## バージョン確認
npx eslint -v
or
./node_modules/.bin/eslint src -v

<出力結果>
v6.6.0

## .eslintrc.json作成
 npx eslint --init

色々聞かれるが、とりあえず全部ENTERキー押下

module.exports = {
    "env": {
        "browser": true,
        "es6": true
    },
    "extends": "eslint:recommended",
    "globals": {
        "Atomics": "readonly",
        "SharedArrayBuffer": "readonly"
    },
    "parserOptions": {
        "ecmaFeatures": {
            "jsx": true
        },
        "ecmaVersion": 2018,
        "sourceType": "module"
    },
    "plugins": [
        "react"
    ],
    "rules": {
    }
};

function test() {
    var message = 'test';;
    var List = ["a",,'b',"c"];
}

## 実行
npx eslint test.js

<出力結果>
 1:10  error  'test' is defined but never used              no-unused-vars
  2:9   error  'message' is assigned a value but never used  no-unused-vars
  2:26  error  Unnecessary semicolon                         no-extra-semi
  3:9   error  'List' is assigned a value but never used     no-unused-vars
  3:16  error  Unexpected comma in middle of array           no-sparse-arrays

✖ 5 problems (5 errors, 0 warnings)
  1 error and 0 warnings potentially fixable with the `--fix` option.

No ESLint configuration found in /home/user/eslint.

## 全ファイルチェック
npx eslint *.js