@cybozu/eslint-config

An ESLint rule set for Cybozu.

This package is intended to use in Cybozu. Currently, this is still in development so the rules might be changed.

What is this?

This is an ESLint rule set for Cybozu. The purpose of @cybozu/eslint-config are the following

• Share best practices for JavaScript
• Standardize JavaScript coding guideline in Cybozu
• Installation support for ESLint and continuous support for the rule set

The benefits to adopt this rule

You don't need to care about updates for ESLint and ESLint plugins. We'll manage the updates and provide CHANGELOG that you need to know so that you can update it easily. In addition, we'll add some useful plugins into @cybozu/eslint-config so you can learn about best practices for JavaScript through @cybozu/eslint-config.

Rule set policies

We provide rules that are Error or Warning.

Error

This is a rule you must fix because the code might not follow our practices in JavaScript

Warning

This is a rule you should fix because the code style might not be preferable.

Version policy

1. We update major version if the changes might cause new errors.
2. We update minor version if the changes might cause new warnings.
3. We update patch version if the changes don't cause any new errors and warnings.

How to use

Install eslint and @cybozu/eslint-config

% npm install --save-dev eslint @cybozu/eslint-config

eslint.config.mjs

Put it into your eslint.config.mjs

import reactTypeScriptPrettier from "@cybozu/eslint-config/presets/react-typescript-prettier";

export default [
  ...reactTypeScriptPrettier,
  // You can add other presets as needed.
  // ...otherPresets
  {
    rules: {
      // You can also override individual rules.
    },
  },
];

Note: Currently, we adopt that indent rule is 2 spaces and having indentation in switch case. You can override the rule if your project adopts 4 spaces or others. We think it's important to have consistency in your entire codebase.

Upgrading from v25 or earlier

Starting from v26, @cybozu/eslint-config only supports Flat Config (eslint.config.mjs) and has dropped support for the legacy config format (.eslintrc.js).

If you are using v25 or earlier, you need to:

• Migrate your ESLint configuration from .eslintrc.js to eslint.config.mjs
• Update all config imports from @cybozu/eslint-config/flat/presets/* to @cybozu/eslint-config/presets/*
• Update import from @cybozu/eslint-config/flat/globals/kintone to @cybozu/eslint-config/globals/kintone

See the ESLint migration guide for details on migrating to Flat Config.

.eslintrc.js (v25 and earlier)

Note: This format is no longer supported in v26 and later. Use eslint.config.mjs instead.

module.exports = {
  extends: "@cybozu",
};

module.exports = {
  extends: "@cybozu/eslint-config/presets/react-typescript-prettier",
  rules: {
    // default
    // 'indent': ['warn', 2, { "SwitchCase": 1 }],
    indent: ["warn", 4, { SwitchCase: 0 }],
  },
};

Support rule set

• @cybozu/eslint-config/presets/base
  • This is included in the all following presets
• @cybozu/eslint-config/presets/node
  • Including eslint-plugin-n
• @cybozu/eslint-config/presets/typescript
  • Including @typescript-eslint/eslint-plugin
• @cybozu/eslint-config/presets/react
  • Including eslint-plugin-react, eslint-plugin-jsx-a11y and eslint-plugin-react-hooks
• @cybozu/eslint-config/presets/react-typescript
  • Including @cybozu/eslint-config/presets/typescript and @cybozu/eslint-config/presets/react
• @cybozu/eslint-config/presets/es5
• @cybozu/eslint-config/presets/css-baseline
  • CSS baseline rules using @eslint/css

Prettier Support

Prettier is a code formatter, which supports not only JavaScript but also many languages. Prettier is widely used as a code formatter for JavaScript.

It's opinionated but we don't have to discuss about code styles with Prettier because it's the rule (No more bikeshed).

The following presets disable all rules that conflict with Prettier and treat the differences between Prettier's code format as errors. You can fix the errors by --fix option so you don't have to fix the errors manually.

To use the presets, you have to install prettier. We only support Prettier v2 or later versions.

% npm install --save-dev prettier

• @cybozu/eslint-config/presets/prettier
• @cybozu/eslint-config/presets/node-prettier
• @cybozu/eslint-config/presets/node-typescript-prettier
• @cybozu/eslint-config/presets/typescript-prettier
• @cybozu/eslint-config/presets/react-typescript-prettier
• @cybozu/eslint-config/presets/react-prettier
• @cybozu/eslint-config/presets/es5-prettier

Currently, we don't support customized Prettier config

React Support

⚠️ Classic JSX Syntax

@cybozu/eslint-config is intended to be used with the New JSX Transform. If you want to use the Classic JSX Transform (React.createElement), please enable the react/jsx-uses-react rule on your own.

rules: {
  "react/jsx-uses-react": "error"
}

For kintone customize developers

We also provide presets for kintone customize/plug-in developers, which include some globals for kintone.

Usage

// eslint.config.mjs
import kintoneCustomize from "@cybozu/eslint-config/presets/kintone-customize";

export default [...kintoneCustomize];

Presets

• @cybozu/eslint-config/presets/kintone-customize
  • Preset for kintone customize/plug-in development
• @cybozu/eslint-config/presets/kintone-customize-prettier
  • Preset for kintone customize/plug-in development including prettier config
• @cybozu/eslint-config/presets/kintone-customize-es5
  • Preset for kintone customize/plug-in development in ES5
• @cybozu/eslint-config/presets/kintone-customize-es5-prettier
  • Preset for kintone customize/plug-in development in ES5 including prettier config