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tessl/npm-eslint-config-prettier

Turns off all rules that are unnecessary or might conflict with Prettier.

Workspace
tessl
Visibility
Public
Created
Last updated
Describes
npmpkg:npm/eslint-config-prettier@10.1.x

To install, run

npx @tessl/cli install tessl/npm-eslint-config-prettier@10.1.0

index.mddocs/

ESLint Config Prettier

ESLint Config Prettier is an ESLint configuration package that disables all formatting rules that might conflict with Prettier, enabling seamless integration between ESLint and Prettier in JavaScript/TypeScript projects. It supports both legacy eslintrc configuration files and the new flat config format, automatically handles various ESLint plugins, and includes a CLI helper tool to identify configuration conflicts.

Package Information

  • Package Name: eslint-config-prettier
  • Package Type: npm
  • Language: JavaScript
  • Installation: npm install --save-dev eslint-config-prettier

Core Imports

ESLint configuration (eslintrc):

{
  "extends": ["prettier"]
}

Flat config (ESLint 9+):

import eslintConfigPrettier from "eslint-config-prettier/flat";

export default [
  // other configs...
  eslintConfigPrettier,
];

CommonJS flat config:

const eslintConfigPrettier = require("eslint-config-prettier/flat");

module.exports = [
  // other configs...
  eslintConfigPrettier,
];

Programmatic access to utilities:

// Main configuration object
const eslintConfigPrettier = require("eslint-config-prettier");

// Prettier-specific rules
const prettierRules = require("eslint-config-prettier/prettier");

// CLI helper functions
const { processRules } = require("eslint-config-prettier/bin/cli");

// Rule validators
const validators = require("eslint-config-prettier/bin/validators");

Basic Usage

Legacy ESLint Configuration

Add to your .eslintrc.json:

{
  "extends": [
    "some-other-config-you-use",
    "prettier"
  ]
}

Flat Config (ESLint 9+)

Add to your eslint.config.js:

import someConfig from "some-other-config-you-use";
import eslintConfigPrettier from "eslint-config-prettier/flat";

export default [
  someConfig,
  eslintConfigPrettier,
];

CLI Conflict Detection

Check for conflicting rules:

npx eslint-config-prettier path/to/main.js

Capabilities

Main Configuration

The primary ESLint configuration that disables all formatting rules conflicting with Prettier.

/**
 * Main ESLint configuration object with disabled formatting rules
 * Contains hundreds of rules set to either "off" or 0 (special rules)
 */
const eslintConfigPrettier: {
  rules: Record<string, 0 | "off">;
};

module.exports = eslintConfigPrettier;

The main configuration includes:

  • Regular rules: Set to "off" - rules that directly conflict with Prettier
  • Special rules: Set to 0 - rules that can be used with specific options (see Special Rules section)
  • Plugin rules: Rules from various ESLint plugins that conflict with Prettier formatting

Usage in eslintrc:

{
  "extends": ["prettier"]
}

Programmatic usage:

const eslintConfigPrettier = require("eslint-config-prettier");
console.log(Object.keys(eslintConfigPrettier.rules).length);
// 300+ rules (depending on ESLINT_CONFIG_PRETTIER_NO_DEPRECATED setting)

Flat Config

ESLint flat config version with name property for better tooling integration.

/**
 * Flat config version with name property
 */
const eslintConfigPrettierFlat: {
  name: "config-prettier";
  rules: Record<string, 0 | "off">;
};

export = eslintConfigPrettierFlat;

Usage:

import eslintConfigPrettier from "eslint-config-prettier/flat";

export default [
  eslintConfigPrettier,
];

Prettier-Specific Rules

Additional rules that can cause issues when using eslint-plugin-prettier.

/**
 * Rules that may conflict with eslint-plugin-prettier
 * These are safe to use as long as the "prettier/prettier" rule from
 * eslint-plugin-prettier isn't enabled
 */
const prettierRules: {
  rules: {
    "arrow-body-style": 0;
    "prefer-arrow-callback": 0;
  };
};

module.exports = prettierRules;

The prettier rules configuration disables:

  • arrow-body-style: Controls arrow function body style (set to 0 as special rule)
  • prefer-arrow-callback: Prefers arrow functions as callbacks (set to 0 as special rule)

These rules use 0 instead of "off" to indicate they are special rules that can be used safely in specific situations.

Usage:

const prettierRules = require("eslint-config-prettier/prettier");
console.log(prettierRules.rules);
// { "arrow-body-style": 0, "prefer-arrow-callback": 0 }

CLI Helper Tool

Command-line tool for detecting ESLint rules that conflict with Prettier.

/**
 * Process ESLint rules and detect conflicts with Prettier
 * @param configRules - Array of [ruleName, value, source] tuples from ESLint config
 * @returns Object with stdout, stderr messages and exit code
 */
function processRules(configRules: Array<[string, any, string]>): {
  stdout?: string;
  stderr?: string;
  code: 0 | 1 | 2;
};

Programmatic Usage:

const { processRules } = require("eslint-config-prettier/bin/cli");

// Example rule configuration
const configRules = [
  ["indent", ["error", 2], "src/config.js"],
  ["quotes", ["error", "single"], "src/config.js"]
];

const result = processRules(configRules);
console.log(result);
// { stdout: "...", code: 2 }

Command Usage:

# Check single file
npx eslint-config-prettier index.js

# Check multiple files
npx eslint-config-prettier index.js test/index.js src/app.js

# With environment variables
ESLINT_USE_FLAT_CONFIG=true npx eslint-config-prettier index.js
ESLINT_CONFIG_PRETTIER_NO_DEPRECATED=true npx eslint-config-prettier index.js

Exit Codes:

  • 0: No problems found
  • 1: General error
  • 2: Conflicting rules found

Rule Validators

Validation functions for special rules that require specific configuration options.

/**
 * Validator functions for special ESLint rules
 * Module export from eslint-config-prettier/bin/validators
 */
const validators: {
  /**
   * Validates curly brace rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  curly(config: { options: any[] }): boolean;
  
  /**
   * Validates lines-around-comment rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  "lines-around-comment"(config: { options: any[] }): boolean;
  
  /**
   * Validates no-confusing-arrow rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  "no-confusing-arrow"(config: { options: any[] }): boolean;
  
  /**
   * Validates no-tabs rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  "no-tabs"(config: { options: any[] }): boolean;
  
  /**
   * Validates unicorn/template-indent rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  "unicorn/template-indent"(config: { options: any[] }): boolean;
  
  /**
   * Validates vue/html-self-closing rule options
   * @param config - Object containing options array from ESLint rule config
   * @returns true if config is compatible with Prettier
   */
  "vue/html-self-closing"(config: { options: any[] }): boolean;
};

module.exports = validators;

Programmatic Usage:

const validators = require("eslint-config-prettier/bin/validators");

// Validate a curly rule configuration
const curlyConfig = { options: ["all"] };
const isCompatible = validators.curly(curlyConfig);
console.log(isCompatible); // true

// Validate lines-around-comment rule
const commentConfig = { 
  options: [{ 
    allowBlockStart: true, 
    allowBlockEnd: true,
    allowObjectStart: true,
    allowObjectEnd: true,
    allowArrayStart: true,
    allowArrayEnd: true
  }] 
};
const isCommentCompatible = validators["lines-around-comment"](commentConfig);
console.log(isCommentCompatible); // true

Supported Plugins

ESLint Config Prettier automatically handles formatting rules from these plugins:

  • @babel/eslint-plugin: Babel-specific ESLint rules
  • @stylistic/eslint-plugin: Stylistic formatting rules (new ESLint stylistic plugin)
  • @typescript-eslint/eslint-plugin: TypeScript-specific ESLint rules
  • eslint-plugin-babel: Legacy Babel ESLint plugin
  • eslint-plugin-flowtype: Flow type checking rules
  • eslint-plugin-react: React-specific ESLint rules
  • eslint-plugin-standard: JavaScript Standard Style rules
  • eslint-plugin-unicorn: Various awesome ESLint rules
  • eslint-plugin-vue: Vue.js-specific ESLint rules

Environment Variables

ESLINT_CONFIG_PRETTIER_NO_DEPRECATED

Excludes deprecated ESLint rules from the configuration when set to any non-empty value.

# Exclude deprecated rules
ESLINT_CONFIG_PRETTIER_NO_DEPRECATED=true npx eslint-config-prettier index.js

ESLINT_USE_FLAT_CONFIG

Controls which ESLint configuration format the CLI tool uses:

# Force flat config
ESLINT_USE_FLAT_CONFIG=true npx eslint-config-prettier index.js

# Force legacy config
ESLINT_USE_FLAT_CONFIG=false npx eslint-config-prettier index.js

# Auto-detect (default)
npx eslint-config-prettier index.js

Special Rules

Some rules require special attention and can be enabled with specific configurations:

curly

Can be used with options other than "multi-line" or "multi-or-nest":

{
  "rules": {
    "curly": ["error", "all"]
  }
}

lines-around-comment

Can be used with specific allow options:

{
  "rules": {
    "lines-around-comment": ["error", {
      "allowBlockStart": true,
      "allowBlockEnd": true,
      "allowObjectStart": true,
      "allowObjectEnd": true,
      "allowArrayStart": true,
      "allowArrayEnd": true
    }]
  }
}

no-confusing-arrow

Can be used with allowParens: false:

{
  "rules": {
    "no-confusing-arrow": ["error", { "allowParens": false }]
  }
}

no-tabs

Can be used with allowIndentationTabs: true:

{
  "rules": {
    "no-tabs": ["error", { "allowIndentationTabs": true }]
  }
}

Error Handling

The CLI tool provides structured error reporting:

  • Regular conflicts: Rules that directly conflict with Prettier formatting
  • Options conflicts: Rules enabled with options that may conflict
  • Special rule warnings: Rules that require manual verification
  • Prettier plugin conflicts: Rules that conflict when using eslint-plugin-prettier

Advanced Usage

Multiple Configuration Files

For projects with different ESLint configurations for different file types:

npx eslint-config-prettier src/index.js test/index.js config/webpack.js

Integration with eslint-plugin-prettier

When using both packages together:

{
  "extends": [
    "some-config",
    "plugin:prettier/recommended"
  ]
}

The plugin:prettier/recommended configuration includes eslint-config-prettier automatically.