eslint-plugin-jsonc

What is eslint-plugin-jsonc?

eslint-plugin-jsonc is an ESLint plugin that provides linting rules for JSON and JSONC (JSON with comments) files. It helps ensure consistency and correctness in JSON files by enforcing specific coding standards and best practices.

What are eslint-plugin-jsonc's main functionalities?

Enforce Consistent Indentation

This rule enforces consistent indentation in JSON files. The example configures the rule to use 2 spaces for indentation.

{
  "rules": {
    "jsonc/indent": ["error", 2]
  }
}

Disallow Trailing Commas

This rule disallows trailing commas in JSON files, which can help prevent syntax errors in environments that do not support them.

{
  "rules": {
    "jsonc/no-trailing-comma": "error"
  }
}

Require Property Keys to be in CamelCase

This rule enforces that property keys in JSON files are written in camelCase, promoting a consistent naming convention.

{
  "rules": {
    "jsonc/camelcase": "error"
  }
}

Disallow Comments

This rule disallows comments in JSON files, ensuring that the files remain pure JSON without any additional annotations.

{
  "rules": {
    "jsonc/no-comments": "error"
  }
}

Other packages similar to eslint-plugin-jsonc

eslint-plugin-json

eslint-plugin-json is another ESLint plugin for linting JSON files. It provides basic rules for JSON file validation but does not support JSONC (JSON with comments). It is simpler and may be more suitable for projects that do not require JSONC support.

jsonlint

jsonlint is a standalone JSON parser and validator. It can be used to check the syntax of JSON files and ensure they are valid. Unlike eslint-plugin-jsonc, jsonlint is not an ESLint plugin and does not integrate with ESLint's rule system.

README

Introduction

eslint-plugin-jsonc is ESLint plugin for JSON, JSONC and JSON5 files.

Features

This ESLint plugin provides linting rules relate to better ways to help you avoid problems when using JSON, JSONC and JSON5.

• You can apply rules similar to the rules you use for JavaScript to JSON using the shareable config "plugin:jsonc/auto-config" provided by this plugin.
• You can choose the appropriate config provided by this plugin depending on whether you are using JSON, JSONC or JSON5.

You can check on the Online DEMO.

Why is it ESLint plugin?

ESLint is a great linter for JavaScript.
Since JSON is a subset of JavaScript, the same parser and rules can be applied to JSON.
Also, JSONC and JSON5, which are variants of JSON, are more similar to JavaScript than JSON. Applying a JavaScript linter to JSON is more rational than creating a JSON-specific linter.

How does eslint-plugin-jsonc work?

This plugin parses .json with its own parser, but this parser just converts AST parsed by espree (ESLint standard parser) into AST with another name. However, AST that does not exist in JSON and JSON5 will be reported as a parse error. By converting the AST to another name, we prevent false positives from ESLint standard rules.
Moreover, You can do the same linting using the extended rules of the ESLint core rules provided by this plugin.

Documentation

See documents.

Installation

npm install --save-dev eslint eslint-plugin-jsonc

Requirements

• ESLint v6.0.0 and above
• Node.js v8.10.0 and above

Usage

Create .eslintrc.* file to configure rules. See also: http://eslint.org/docs/user-guide/configuring.

Example .eslintrc.js:

module.exports = {
  extends: [
    // add more generic rulesets here, such as:
    // 'eslint:recommended',
    'plugin:jsonc/recommended-with-jsonc'
  ],
  rules: {
    // override/add rules settings here, such as:
    // 'jsonc/rule-name': 'error'
  }
}

Configs

This plugin provides configs:

• plugin:jsonc/base ... Configuration to enable correct JSON parsing.
• plugin:jsonc/recommended-with-json ... Recommended configuration for JSON.
• plugin:jsonc/recommended-with-jsonc ... Recommended configuration for JSONC.
• plugin:jsonc/recommended-with-json5 ... Recommended configuration for JSON5.
• plugin:jsonc/auto-config ... Automatically apply jsonc rules similar to your configured ESLint core rules to JSON.

Running ESLint from the command line

If you want to run eslint from the command line, make sure you include the .json extension using the --ext option or a glob pattern, because ESLint targets only .js files by default.

Examples:

eslint --ext .js,.json src
eslint "src/**/*.{js,json}"

Editor Integrations

Visual Studio Code

Use the dbaeumer.vscode-eslint extension that Microsoft provides officially.

You have to configure the eslint.validate option of the extension to check .json files, because the extension targets only *.js or *.jsx files by default.

Example .vscode/settings.json:

{
  "eslint.validate": [
    "javascript",
    "javascriptreact",
    "json",
    "jsonc",
    "json5"
  ]
}

Rules

The --fix option on the command line automatically fixes problems reported by rules which have a wrench :wrench: below.
The rules with the following star :star: are included in the config.

JSONC Rules

Rule ID	Description	Fixable	JSON	JSONC	JSON5
jsonc/no-comments	disallow comments		:star:
jsonc/valid-json-number	disallow invalid number for JSON	:wrench:	:star:	:star:

Extension Rules

Rule ID	Description	Fixable	JSON	JSONC	JSON5
jsonc/array-bracket-newline	enforce line breaks after opening and before closing array brackets	:wrench:
jsonc/array-bracket-spacing	disallow or enforce spaces inside of brackets	:wrench:
jsonc/array-element-newline	enforce line breaks between array elements	:wrench:
jsonc/comma-dangle	require or disallow trailing commas	:wrench:	:star:
jsonc/comma-style	enforce consistent comma style	:wrench:
jsonc/indent	enforce consistent indentation	:wrench:
jsonc/key-spacing	enforce consistent spacing between keys and values in object literal properties	:wrench:
jsonc/no-dupe-keys	disallow duplicate keys in object literals		:star:	:star:	:star:
jsonc/no-multi-str	disallow multiline strings		:star:	:star:
jsonc/no-octal-escape	disallow octal escape sequences in string literals
jsonc/no-useless-escape	disallow unnecessary escape usage		:star:	:star:	:star:
jsonc/object-curly-newline	enforce consistent line breaks inside braces	:wrench:
jsonc/object-curly-spacing	enforce consistent spacing inside braces	:wrench:
jsonc/object-property-newline	enforce placing object properties on separate lines	:wrench:
jsonc/quote-props	require quotes around object literal property names	:wrench:	:star:	:star:
jsonc/quotes	enforce use of double or single quotes	:wrench:	:star:	:star:
jsonc/sort-keys	require object keys to be sorted

Contributing

Welcome contributing!

Please use GitHub's Issues/PRs.

Development Tools

• npm test runs tests and measures coverage.
• npm run update runs in order to update readme and recommended configuration.

License

See the LICENSE file for license rights and limitations (MIT).