eslint, prettier, semistandard, standard, and xo are all tools used to enforce code quality, consistency, and formatting in JavaScript projects. eslint is a highly configurable linter that identifies problematic patterns or code that doesn’t adhere to defined rules. prettier is an opinionated code formatter that automatically formats code to ensure consistent style without manual intervention. standard, semistandard, and xo are zero-config or minimal-config toolchains that bundle linting (and sometimes formatting) with predefined rule sets—standard enforces a strict style with no semicolons, semistandard is a variant that allows semicolons, and xo offers a modern, opinionated set of rules with built-in Prettier integration and support for the latest JavaScript features.
JavaScript Code Quality Tools Compared: ESLint, Prettier, Standard, Semistandard, and XO
Choosing the right tool to enforce code quality and style in JavaScript isn’t just about preferences — it affects onboarding speed, code review efficiency, and long-term maintainability. While all five tools (eslint, prettier, semistandard, standard, xo) aim to reduce noise in codebases, they differ significantly in scope, configurability, and philosophy. Let’s break down how they work in practice.
🔍 Core Purpose: Linting vs Formatting vs Bundled Opinions
eslint is a linter: it analyzes code for potential errors, anti-patterns, and style violations based on configurable rules.
// .eslintrc.js
module.exports = {
rules: {
'no-console': 'warn',
'quotes': ['error', 'single']
}
};
// Running: npx eslint src/
// Catches logic issues AND style, but only if rules are defined
prettier is a formatter: it rewrites code to match a consistent visual style, ignoring logic concerns.
// .prettierrc
{
"semi": true,
"singleQuote": true
}
// Running: npx prettier --write src/
// Turns this:
const x={a:1,b:2};
// Into this:
const x = { a: 1, b: 2 };
standard, semistandard, and xo are opinionated bundles: they combine linting (and sometimes formatting) with fixed rule sets and minimal or no configuration.
// standard: no config needed
// Fails on semicolons, requires 2-space indent
const name = 'Alice' // ✅
const name = 'Alice'; // ❌
// semistandard: same as standard but allows semicolons
const name = 'Alice'; // ✅
// xo: includes Prettier + modern ESLint rules
// Enforces async/await over callbacks, const over var, etc.
⚙️ Configuration Flexibility: Zero-Config vs Full Control
standard, semistandard, and xo promote zero-config workflows, but with different escape hatches.
standardallows no configuration — not even.eslintrc. Overrides require comments like/* eslint-disable */.semistandardbehaves identically but permits semicolons; also no config file support.xosupports limited configuration viaxoproperty inpackage.json:
{
"xo": {
"semicolon": false,
"rules": {
"no-console": "off"
}
}
}
In contrast, eslint thrives on customization:
// Full control over parsers, plugins, environments
module.exports = {
extends: ['eslint:recommended', 'plugin:react/recommended'],
parserOptions: { ecmaVersion: 2022 },
env: { browser: true, node: true }
};
prettier sits in the middle: it has a small set of options (e.g., printWidth, tabWidth), but once set, it enforces them universally.
🧩 Integration: Can They Work Together?
Yes — and often should. prettier handles formatting; eslint handles logic and subtle style rules. But they can conflict (e.g., both trying to fix quotes). The solution is eslint-config-prettier, which disables ESLint rules that overlap with Prettier.
// .eslintrc.js with Prettier
module.exports = {
extends: [
'eslint:recommended',
'prettier' // turns off conflicting rules
],
plugins: ['prettier'],
rules: {
'prettier/prettier': 'error'
}
};
xo already includes this integration out of the box. standard and semistandard do not support Prettier natively — mixing them requires disabling their formatting rules manually, which defeats their zero-config promise.
🛑 Maintenance and Modern JavaScript Support
As of 2024:
eslintandprettierare actively maintained and support the latest ECMAScript proposals via plugins (e.g.,@babel/eslint-parser).xois actively maintained, defaults to modern JS (ES2022+), and auto-enables environments like Node.js 18+.standardis maintained but updates slowly; it supports modern JS but may lag behind cutting-edge syntax.semistandardhas not seen significant updates since 2020 and relies on older versions ofstandard. While not officially deprecated, it should be avoided in new projects due to stale dependencies and lack of ESNext support.
⚠️ Important:
semistandardis effectively unmaintained. Usestandardwith semicolon overrides via ESLint, or switch toxoif you need semicolons and modern tooling.
🧪 Real-World Workflow Examples
Scenario 1: Large Enterprise Frontend Monorepo
You need TypeScript support, React hooks rules, custom security checks, and team-specific naming conventions.
- ✅ Best choice:
eslint+prettier - Why? Full control over rules, plugin ecosystem, and incremental adoption.
// Example ESLint config for enterprise
module.exports = {
extends: [
'@typescript-eslint/recommended',
'plugin:react-hooks/recommended',
'prettier'
],
rules: {
'security/detect-object-injection': 'error',
'@typescript-eslint/explicit-function-return-type': 'warn'
}
};
Scenario 2: Open-Source CLI Tool (Node.js)
You want fast setup, modern JS, and consistent formatting without config debates.
- ✅ Best choice:
xo - Why? Zero-config with sane defaults, built-in Prettier, and Node.js-aware rules.
// package.json
{
"scripts": {
"test": "xo && node test.js"
},
"xo": {
"envs": ["node"],
"ignores": ["dist/"]
}
}
Scenario 3: Legacy Project Migration
Your codebase uses semicolons and you want minimal disruption while catching bugs.
- ✅ Best choice:
eslintwitheslint-config-standard+ semicolon override - Why?
semistandardis outdated; better to use a maintained base and customize.
// .eslintrc.js
module.exports = {
extends: 'standard',
rules: {
'semi': ['error', 'always']
}
};
Scenario 4: Solo Developer Building a Prototype
You just want clean code without thinking about tooling.
- ✅ Best choice:
standard(if you accept no semicolons) orxo(if you prefer more modern defaults) - Avoid
semistandarddue to maintenance concerns.
📊 Summary Table
| Package | Type | Configurable? | Includes Formatter? | Modern JS Ready | Maintenance Status |
|---|---|---|---|---|---|
eslint | Linter | ✅ Full | ❌ | ✅ (with plugins) | Actively maintained |
prettier | Formatter | ⚠️ Limited | ✅ | ✅ | Actively maintained |
standard | Linter bundle | ❌ | ❌ | ⚠️ Partial | Maintained |
semistandard | Linter bundle | ❌ | ❌ | ❌ (outdated) | Unmaintained |
xo | Linter+Formatter | ⚠️ Minimal | ✅ (via Prettier) | ✅ | Actively maintained |
💡 Final Recommendation
- Need maximum control? → Use
eslint+prettier. - Want modern defaults with minimal setup? → Use
xo. - Prefer the original zero-config experience and accept its constraints? → Use
standard. - Avoid
semistandard— it’s outdated and offers no advantage over configuringstandardor usingxo.
Remember: formatting and linting solve different problems. For production-grade applications, combining a powerful linter (eslint or xo) with an automatic formatter (prettier) gives you the best of both worlds — consistent style and robust code quality checks.
- eslint:
Choose
eslintwhen you need fine-grained control over code quality rules, custom rule definitions, or integration with complex build systems. It’s ideal for large teams or mature codebases that require tailored linting policies, plugin ecosystems (e.g., React, TypeScript), or gradual adoption of stricter standards. However, it requires explicit configuration and maintenance overhead. - prettier:
Choose
prettierwhen your primary goal is automatic, consistent code formatting with minimal debate over style. It works best when paired with a linter like ESLint for logic-focused checks, as Prettier only handles formatting (spacing, line breaks, quotes). Avoid using it alone if you need to catch bugs or enforce non-stylistic best practices. - standard:
Choose
standardfor rapid project setup with strong opinions: no semicolons, 2-space indentation, and automatic error detection for common pitfalls. It’s great for solo developers or small teams that align with its philosophy and want to avoid configuration debates. But if your team prefers semicolons or needs to tweak rules, you’ll quickly outgrow it. - xo:
Choose
xowhen you want a modern, opinionated linter that combines ESLint rules with built-in Prettier formatting, supports ESNext syntax by default, and encourages up-to-date JavaScript practices. It’s well-suited for Node.js and frontend projects that value convention over configuration but still benefit from occasional overrides via minimal config files. - semistandard:
Choose
semistandardif you want a zero-configuration linter that enforces a clean code style but permits semicolons—making it a good middle ground for teams migrating from traditional JavaScript conventions. However, it’s less actively maintained than alternatives and offers little customization, so it’s best suited for small projects or prototyping where setup time matters more than long-term flexibility.
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
- License
- Team
- Sponsors
- Technology Sponsors
Installation and Usage
Prerequisites: Node.js (^18.18.0, ^20.9.0, or >=21.1.0) built with SSL support. (If you are using an official Node.js distribution, SSL is always built in.)
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.
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.
