@prefer-jsr/eslint-plugin-prefer-jsr

An ESLint plugin that suggests using JSR packages over NPM when available.

Installation

pnpm i jsr:@prefer-jsr/eslint-plugin-prefer-jsr

yarn add jsr:@prefer-jsr/eslint-plugin-prefer-jsr

npx jsr add @prefer-jsr/eslint-plugin-prefer-jsr

npm install --save-dev @prefer-jsr/eslint-plugin-prefer-jsr

With new ESLint JSON language feature (recommended)

pnpm i jsr:@eslint/json

yarn add jsr:@eslint/json

npx jsr add @eslint/json

npm install --save-dev @eslint/json

With the legacy JSON parser

pnpm add -D jsonc-eslint-parser

yarn add -D jsonc-eslint-parser

npm install --save-dev jsonc-eslint-parser

Usage

This plugin works with package.json files and supports both the new @eslint/json parser and the legacy jsonc-eslint-parser.

Recommended Config

One way to use this plugin is with the recommended config:

// eslint.config.js
import { defineConfig } from 'eslint/config';
import preferJsr from '@prefer-jsr/eslint-plugin-prefer-jsr';
import json from '@eslint/json';

export default defineConfig([
  {
    plugins: {
      preferJsr,
      json,
    },
    extends: ['prefer-jsr/recommended'],
  },
]);

The recommended config automatically:

• Applies to **/package.json files
• Enables the @prefer-jsr/prefer-jsr rule with error severity

Flat Config (ESLint 9+) with @eslint/json

For more control, you can configure the plugin manually:

// eslint.config.js
import preferJsr from '@prefer-jsr/eslint-plugin-prefer-jsr';
import json from '@eslint/json';

export default [
  {
    files: ['package.json'],
    language: 'json/json',
    plugins: {
      '@prefer-jsr': preferJsr,
      json,
    },
    rules: {
      '@prefer-jsr/prefer-jsr': 'error',
    },
  },
];

Flat Config (ESLint 9+) with jsonc-eslint-parser (legacy)

// eslint.config.js
import preferJsr from '@prefer-jsr/eslint-plugin-prefer-jsr';
import jsoncParser from 'jsonc-eslint-parser';

export default [
  {
    files: ['package.json'],
    languageOptions: {
      parser: jsoncParser,
    },
    plugins: {
      '@prefer-jsr': preferJsr,
    },
    rules: {
      '@prefer-jsr/prefer-jsr': 'error',
    },
  },
];

Rules

prefer-jsr

This rule warns when a dependency in package.json has a JSR equivalent available.

example mappings:

• zod → @zod/zod
• @eslint/markdown → @eslint/markdown

Configuration

The rule accepts an options object with the following properties:

• ignore (array): List of package names to ignore

Examples

Basic usage:

{
  rules: {
    '@prefer-jsr/prefer-jsr': 'error',
  },
}

Ignoring specific packages:

{
  rules: {
    '@prefer-jsr/prefer-jsr': ['error', {
      ignore: ['legacy-package', 'special-case']
    }],
  },
}

Valid

{
  "dependencies": {
    "@zod/zod": "jsr:^4.1.12"
  }
}

Invalid

{
  "dependencies": {
    "zod": "^4.1.12"
  }
}

Auto-fix available: The rule can automatically replace NPM dependencies with their JSR equivalents.

Features

• 🔍 Detection: Identifies NPM dependencies that have JSR equivalents
• 🔧 Auto-fix: Automatically replaces NPM imports with JSR versions
• 📦 Package.json support: Works with all dependency types (dependencies, devDependencies, peerDependencies, optionalDependencies)
• 🎯 Modern: Uses @eslint/json for proper JSON language support

Dependencies

This plugin specifically supports JSR packages that have been identified as having NPM equivalents. The mapping is maintained in the plugin and can be extended over time.

Contributing

Building

Run nx build eslint-plugin to build the library.

Running unit tests

Run nx test eslint-plugin to execute the unit tests via Vitest.