JavaScriptコードの品質保証とスタイル強制のためのリンターツール比較
eslint、semistandard、standard、xo はすべて JavaScript プロジェクトにおけるコード品質の維持やコーディング規約の自動適用を目的としたツールです。これらは静的解析（リンティング）を行い、潜在的なバグやスタイル違反を検出します。eslint は高度にカスタマイズ可能なルールエンジンを提供し、他の3つは eslint をベースにした「プリセット」または「オピニオン型」の設定として機能します。standard はセミコロン不要・2スペースインデントなど独自のスタイルを採用し、semistandard はそれに対してセミコロンを許容する変種です。xo は現代的な JavaScript（ESNext、TypeScript 対応など）に特化し、より積極的なコード修正を推奨します。
npmのダウンロードトレンド
GitHub Starsランキング
統計詳細
JavaScript リンター戦略：eslint vs semistandard vs standard vs xo
フロントエンド開発において、コードの品質と一貫性を保つことは長期的な保守性に直結します。eslint、semistandard、standard、xo はいずれもこの課題に取り組むツールですが、アプローチと適用範囲が大きく異なります。現場の実情に即して、それぞれの特性を深掘りします。
🧩 基本設計思想：柔軟性 vs 決められた道
eslint は「ルールエンジン」として設計されており、すべての設定を明示的に定義する必要があります。
- ルールの有効/無効、エラー/警告レベル、オプションを個別に指定可能
.eslintrc.jsやeslint.config.js（Flat Config）で詳細な設定が可能- プラグインやカスタムルールによる拡張性が非常に高い
// eslint.config.js (Flat Config)
import js from '@eslint/js';
export default [
js.configs.recommended,
{
rules: {
'no-console': 'warn',
'indent': ['error', 2]
}
}
];
standard は「設定不要」をコンセプトに、あらかじめ決められたルールセットを提供します。
- 設定ファイル不要で即時利用可能
- セミコロン不要、2スペースインデント、シングルクォートなど独自スタイルを強制
- カスタマイズは基本的に非推奨（
.standardrcでの一部例外対応あり）
// package.json
{
"scripts": {
"lint": "standard"
},
"devDependencies": {
"standard": "*"
}
}
semistandard は standard の派生版で、唯一の違いは「セミコロンを許容する」点です。
- それ以外のルール（インデント、クォートなど）は
standardと同一 - セミコロン派とノーセミコロン派の間で折衷案が必要なチーム向け
// package.json
{
"scripts": {
"lint": "semistandard"
},
"devDependencies": {
"semistandard": "*"
}
}
xo は「モダン JavaScript 向けのオピニオン型リンター」として設計されています。
- ES2022+ や TypeScript、React JSX への対応が標準で含まれる
- 自動修正（
--fix）を積極的に推奨 - 設定は
package.jsonのxoフィールドまたはxo.config.jsで行う
// package.json
{
"xo": {
"semicolon": false,
"space": true
}
}
🔧 カスタマイズ性：自由度のトレードオフ
ルールの上書き
eslint では任意のルールを自由に上書きできます。
// .eslintrc.js
module.exports = {
rules: {
'no-var': 'error',
'prefer-const': 'warn'
}
};
standard / semistandard では公式にカスタマイズが推奨されていませんが、.eslintrc を併用することで部分的に上書き可能です（非公式なワークアラウンド）。
// .eslintrc.json（standard と併用）
{
"extends": ["./node_modules/standard/eslintrc.json"],
"rules": {
"comma-dangle": "off"
}
}
xo では overrides や rules フィールドで公式にカスタマイズをサポートしています。
// xo.config.js
export default {
rules: {
'unicorn/filename-case': 'off'
}
};
プラグインと統合
eslint は公式プラグイン（@typescript-eslint、eslint-plugin-react など）との統合が標準的です。
// eslint.config.js
import reactPlugin from 'eslint-plugin-react';
export default [
{
plugins: { react: reactPlugin },
rules: { 'react/jsx-uses-react': 'error' }
}
];
xo は内部で eslint を使用しており、react、typescript、vue などのサポートがビルトインされています。
// xo は package.json に "type": "module" があれば自動で ESM 対応
// TypeScript ファイルがあれば自動で型チェックを有効化
一方、standard / semistandard はプラグイン対応が限定的で、主に JavaScript のみを対象とします。
🛠️ 実行と修正：開発体験の差
自動修正機能
すべてのツールが --fix オプションをサポートしていますが、その範囲に差があります。
eslint:
npx eslint --fix src/
standard:
npx standard --fix
semistandard:
npx semistandard --fix
xo:
npx xo --fix
ただし、xo はより積極的に修正を適用し、たとえば未使用の変数を自動削除するなど、eslint のデフォルトルールよりも踏み込んだ修正を行います。
CI 統合
eslint と xo は exit code を適切に返すため、CI での失敗検出が容易です。
# GitHub Actions
- run: npx eslint .
# エラーがあれば自動で job 失敗
standard / semistandard も同様ですが、出力形式が簡素なため、詳細なレポートが必要な場合は eslint + formatter の方が有利です。
🌐 実際のコード例で見る違い
以下のコードを各ツールでチェックした場合の挙動を比較します。
// sample.js
var foo = 'bar'
console.log(foo)
eslint（推奨ルールのみ）:varの使用で警告、末尾セミコロンなしでエラー（ルール次第）standard: セミコロンなしでエラー、var使用でエラー、2スペースでない場合もエラーsemistandard:var使用でエラー（セミコロンは OK）xo:var使用でエラー、末尾セミコロンなしでエラー（デフォルト設定）、さらに未使用変数なら警告
📌 選定ガイド：プロジェクトの成熟度とニーズに合わせて
新規プロジェクトで素早く始めたい
standardまたはsemistandardを選ぶと、設定不要で即座に一貫したスタイルが適用されます。- セミコロンの有無で迷うなら、チームの好みに合わせて選択。
モダン JS / TS プロジェクト
xoが最もスムーズです。TypeScript や JSX のサポートが標準で含まれ、最新の構文にも追随しています。
大規模プロジェクトや複雑な要件
eslintが唯一の選択肢です。細かなルール調整、複数の技術スタックへの対応、カスタムルールの導入などが必須になるためです。
既存プロジェクトの段階的導入
eslintの--init機能で既存コードに合わせたルールを生成し、徐々に厳格化するのが現実的です。standard系は既存コードとの互換性が低く、一括修正が必要になることが多いです。
💡 最終的なアドバイス
- 柔軟性が命 →
eslint - シンプルさが正義 →
standard（セミコロン不要）またはsemistandard（セミコロン可） - 最新技術スタックで高速開発 →
xo
重要なのは、一度選んだツールをチーム全体で徹底し、CI で強制することです。ツール自体よりも、一貫した運用の方が品質向上に大きく貢献します。
選び方: eslint vs semistandard vs standard vs xo
- eslint:
eslintはプロジェクトの要件に完全に合わせてルールを細かく調整したい場合に最適です。大規模チームや複数のサブプロジェクトを持つモノレポ環境では、共通のカスタム設定を共有することで一貫性を保ちつつ柔軟性も確保できます。ただし、初期設定とメンテナンスにはコストがかかります。 - semistandard:
semistandardは Standard スタイルをベースにしつつ、セミコロンの使用を許容したいチーム向けです。Standard の哲学（シンプルで設定不要）を尊重しつつ、セミコロン必須派の開発者にも配慮する妥協点として有効です。既存の Standard コードベースにセミコロンを段階的に導入したい場合にも適しています。 - standard:
standardは「設定不要」を掲げ、最小限の構成で即座に一貫したコードスタイルを適用したい場合に選択します。新規プロジェクトで迅速に開発を始めたい、またはチーム内でスタイル議論を避けたい場合に特に有効です。ただし、ルールのカスタマイズがほぼ不可能なため、特定の規約に強く縛られることになります。 - xo:
xoは最新の JavaScript 機能（ES2022+ や TypeScript）を積極的にサポートし、コードの現代化を促進したい場合に適しています。自動修正機能が充実しており、CI 統合もしやすい設計です。ただし、頻繁に更新されるため、安定性よりも先進性を重視するプロジェクト向きです。
人気の比較
eslint のREADME
ESLint
Website | Configure ESLint | Rules | Contribute to ESLint | Report Bugs | Code of Conduct | X | Discord | Mastodon | Bluesky
ESLint is a tool for identifying and reporting on patterns found in ECMAScript/JavaScript code. In many ways, it is similar to JSLint and JSHint with a few exceptions:
- ESLint uses Espree for JavaScript parsing.
- ESLint uses an AST to evaluate patterns in code.
- ESLint is completely pluggable, every single rule is a plugin and you can add more at runtime.
Table of Contents
- Installation and Usage
- Configuration
- Version Support
- Code of Conduct
- Filing Issues
- Frequently Asked Questions
- Releases
- Security Policy
- Semantic Versioning Policy
- ESM Dependencies
- License
- Team
- Sponsors
- Technology Sponsors
Installation and Usage
Prerequisites
To use ESLint, you must have Node.js (^20.19.0, ^22.13.0, or >=24) installed and built with SSL support. (If you are using an official Node.js distribution, SSL is always built in.)
If you use ESLint's TypeScript type definitions, TypeScript 5.3 or later is required.
npm Installation
You can install and configure ESLint using this command:
npm init @eslint/config@latest
After that, you can run ESLint on any file or directory like this:
npx eslint yourfile.js
pnpm Installation
To use ESLint with pnpm, we recommend setting up a .npmrc file with at least the following settings:
auto-install-peers=true
node-linker=hoisted
This ensures that pnpm installs dependencies in a way that is more compatible with npm and is less likely to produce errors.
Configuration
You can configure rules in your eslint.config.js files as in this example:
import { defineConfig } from "eslint/config";
export default defineConfig([
{
files: ["**/*.js", "**/*.cjs", "**/*.mjs"],
rules: {
"prefer-const": "warn",
"no-constant-binary-expression": "error",
},
},
]);
The names "prefer-const" and "no-constant-binary-expression" are the names of rules in ESLint. The first value is the error level of the rule and can be one of these values:
"off"or0- turn the rule off"warn"or1- turn the rule on as a warning (doesn't affect exit code)"error"or2- turn the rule on as an error (exit code will be 1)
The three error levels allow you fine-grained control over how ESLint applies rules (for more configuration options and details, see the configuration docs).
Version Support
The ESLint team provides ongoing support for the current version and six months of limited support for the previous version. Limited support includes critical bug fixes, security issues, and compatibility issues only.
ESLint offers commercial support for both current and previous versions through our partners, Tidelift and HeroDevs.
See Version Support for more details.
Code of Conduct
ESLint adheres to the OpenJS Foundation Code of Conduct.
Filing Issues
Before filing an issue, please be sure to read the guidelines for what you're reporting:
Frequently Asked Questions
Does ESLint support JSX?
Yes, ESLint natively supports parsing JSX syntax (this must be enabled in configuration). Please note that supporting JSX syntax is not the same as supporting React. React applies specific semantics to JSX syntax that ESLint doesn't recognize. We recommend using eslint-plugin-react if you are using React and want React semantics.
Does Prettier replace ESLint?
No, ESLint and Prettier have different jobs: ESLint is a linter (looking for problematic patterns) and Prettier is a code formatter. Using both tools is common, refer to Prettier's documentation to learn how to configure them to work well with each other.
What ECMAScript versions does ESLint support?
ESLint has full support for ECMAScript 3, 5, and every year from 2015 up until the most recent stage 4 specification (the default). You can set your desired ECMAScript syntax and other settings (like global variables) through configuration.
What about experimental features?
ESLint's parser only officially supports the latest final ECMAScript standard. We will make changes to core rules in order to avoid crashes on stage 3 ECMAScript syntax proposals (as long as they are implemented using the correct experimental ESTree syntax). We may make changes to core rules to better work with language extensions (such as JSX, Flow, and TypeScript) on a case-by-case basis.
In other cases (including if rules need to warn on more or fewer cases due to new syntax, rather than just not crashing), we recommend you use other parsers and/or rule plugins. If you are using Babel, you can use @babel/eslint-parser and @babel/eslint-plugin to use any option available in Babel.
Once a language feature has been adopted into the ECMAScript standard (stage 4 according to the TC39 process), we will accept issues and pull requests related to the new feature, subject to our contributing guidelines. Until then, please use the appropriate parser and plugin(s) for your experimental feature.
Which Node.js versions does ESLint support?
ESLint updates the supported Node.js versions with each major release of ESLint. At that time, ESLint's supported Node.js versions are updated to be:
- The most recent maintenance release of Node.js
- The lowest minor version of the Node.js LTS release that includes the features the ESLint team wants to use.
- The Node.js Current release
ESLint is also expected to work with Node.js versions released after the Node.js Current release.
Refer to the Quick Start Guide for the officially supported Node.js versions for a given ESLint release.
Where to ask for help?
Open a discussion or stop by our Discord server.
Why doesn't ESLint lock dependency versions?
Lock files like package-lock.json are helpful for deployed applications. They ensure that dependencies are consistent between environments and across deployments.
Packages like eslint that get published to the npm registry do not include lock files. npm install eslint as a user will respect version constraints in ESLint's package.json. ESLint and its dependencies will be included in the user's lock file if one exists, but ESLint's own lock file would not be used.
We intentionally don't lock dependency versions so that we have the latest compatible dependency versions in development and CI that our users get when installing ESLint in a project.
The Twilio blog has a deeper dive to learn more.
Releases
We have scheduled releases every two weeks on Friday or Saturday. You can follow a release issue for updates about the scheduling of any particular release.
Security Policy
ESLint takes security seriously. We work hard to ensure that ESLint is safe for everyone and that security issues are addressed quickly and responsibly. Read the full security policy.
Semantic Versioning Policy
ESLint follows semantic versioning. However, due to the nature of ESLint as a code quality tool, it's not always clear when a minor or major version bump occurs. To help clarify this for everyone, we've defined the following semantic versioning policy for ESLint:
- Patch release (intended to not break your lint build)
- A bug fix in a rule that results in ESLint reporting fewer linting errors.
- A bug fix to the CLI or core (including formatters).
- Improvements to documentation.
- Non-user-facing changes such as refactoring code, adding, deleting, or modifying tests, and increasing test coverage.
- Re-releasing after a failed release (i.e., publishing a release that doesn't work for anyone).
- Minor release (might break your lint build)
- A bug fix in a rule that results in ESLint reporting more linting errors.
- A new rule is created.
- A new option to an existing rule that does not result in ESLint reporting more linting errors by default.
- A new addition to an existing rule to support a newly-added language feature (within the last 12 months) that will result in ESLint reporting more linting errors by default.
- An existing rule is deprecated.
- A new CLI capability is created.
- New capabilities to the public API are added (new classes, new methods, new arguments to existing methods, etc.).
- A new formatter is created.
eslint:recommendedis updated and will result in strictly fewer linting errors (e.g., rule removals).
- Major release (likely to break your lint build)
eslint:recommendedis updated and may result in new linting errors (e.g., rule additions, most rule option updates).- A new option to an existing rule that results in ESLint reporting more linting errors by default.
- An existing formatter is removed.
- Part of the public API is removed or changed in an incompatible way. The public API includes:
- Rule schemas
- Configuration schema
- Command-line options
- Node.js API
- Rule, formatter, parser, plugin APIs
According to our policy, any minor update may report more linting errors than the previous release (ex: from a bug fix). As such, we recommend using the tilde (~) in package.json e.g. "eslint": "~3.1.0" to guarantee the results of your builds.
ESM Dependencies
Since ESLint is a CommonJS package, there are restrictions on which ESM-only packages can be used as dependencies.
Packages that are controlled by the ESLint team and have no external dependencies can be safely loaded synchronously using require(esm) and therefore used in any contexts.
For external packages, we don't use require(esm) because a package could add a top-level await and thus break ESLint. We can use an external ESM-only package only in case it is needed only in asynchronous code, in which case it can be loaded using dynamic import().
These policies don't apply to packages intended for our own usage only, such as eslint-config-eslint.
License
MIT License
Copyright OpenJS Foundation and other contributors, <www.openjsf.org>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Team
These folks keep the project moving and are resources for help.
Technical Steering Committee (TSC)
The people who manage releases, review feature requests, and meet regularly to ensure ESLint is properly maintained.
 Nicholas C. Zakas |
 Francesco Trotta |
 Milos Djermanovic |
Reviewers
The people who review and implement new features.
 唯然 |
 Nitin Kumar |
Committers
The people who review and fix bugs and help triage issues.
 fnx |
 Josh Goldberg ✨ |
 Sweta Tanwar |
 Tanuj Kanti |
 루밀LuMir |
 Pixel998 |
Website Team
Team members who focus specifically on eslint.org
 Amaresh S M |
 Harish |
 Percy Ma |
Sponsors
The following companies, organizations, and individuals support ESLint's ongoing maintenance and development. Become a Sponsor to get your logo on our READMEs and website.
Platinum Sponsors
Gold Sponsors
Silver Sponsors
Bronze Sponsors
Technology Sponsors
Technology sponsors allow us to use their products and services for free as part of a contribution to the open source ecosystem and our work.
