Setup ESLint Prettier

install packages

# eslint prettier
$ yarn add -D eslint prettier eslint-config-prettier
# for typescript
$ yarn add -D @typescript-eslint/parser @typescript-eslint/eslint-plugin
# for react
$ yarn add -D eslint-plugin-react eslint-plugin-react-hooks

ESLint settings

$ yarn run eslint --init
✔ How would you like to use ESLint? problems
✔ What type of modules does your project use? esm
✔ Which framework does your project use? react
✔ Does your project use TypeScript? Yes
✔ Where does your code run? browser
✔ What format do you want your config file to be in? JavaScript
✔ Would you like to install them now with npm? Yes

.eslintrc.js

module.exports = {
  env: {
    browser: true,
    es2021: true,
+     // module.exports をエラーにしない
+     node: true,
  },
  extends: [
    'eslint:recommended',
    'plugin:react/recommended',
    'plugin:@typescript-eslint/recommended',
+     'plugin:react-hooks/recommended',
+     'prettier',
  ],
  parser: '@typescript-eslint/parser',
  parserOptions: {
    ecmaFeatures: {
      jsx: true,
    },
    ecmaVersion: 12,
    sourceType: 'module',
+     tsconfigRootDir: __dirname,
+     project: ['./tsconfig.json'],
  },
+   settings: {
+     // React のバージョンを自動検出
+     react: {
+       version: 'detect',
+     },
+   },
  plugins: ['react', '@typescript-eslint'],
  rules: {
  },
};

Prettier

$ touch .prettier.js

.prettier.js

module.exports = {
  trailingComma: 'all',
  tabWidth: 2,
  printWidth: 80,
  singleQuote: true,
  arrowParens: 'always',
  bracketSpacing: true,
  jsxBracketSameLine: false,
  semi: true,
};

VSCode settings

Auto format by editor.

$ mkdir .vscode
$ touch .vscode/settings.json

.vscode/settings.json

{
  "editor.tabSize": 2,
  "eslint.validate": [
    "javascript",
    "javascriptreact",
    "typescript",
    "typescriptreact"
  ],
  "typescript.tsdk": "node_modules/typescript/lib",
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true
  },
  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "editor.formatOnPaste": false,
  "editor.formatOnSave": true,
  "files.exclude": {
    "**/node_modules": true
  },
  "[markdown]": {
    "files.trimTrailingWhitespace": false
  }
}

Check conflict setting

$ npx eslint-config-prettier 'src/**/*.{js,jsx,ts,tsx}'
The following rules are unnecessary or might conflict with Prettier:

- eol-last

---

React Recoil Basic Tutorial

cf. https://recoiljs.org/docs/basic-tutorial/intro

---

Getting Started with Create React App

This project was bootstrapped with Create React App.

Available Scripts

In the project directory, you can run:

yarn start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

yarn test

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

yarn build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

yarn eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.

You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

Learn More

You can learn more in the Create React App documentation.

To learn React, check out the React documentation.