jsonc-eslint-parser

📛 Introduction

JSON, JSONC and JSON5 parser for use with ESLint plugins.

This parser allows us to lint JSON, JSONC and JSON5 files. This parser and the rules of eslint-plugin-jsonc would catch some of the mistakes and code style violations.

See eslint-plugin-jsonc for details.

💿 Installation

npm i --save-dev jsonc-eslint-parser

📖 Usage (Flat Config)

In your ESLint configuration file, set the parser property:

import * as jsoncParser from "jsonc-eslint-parser";

export default [
  {
    // ...
    // Add the following settings.
    files: ["**/*.json", "**/*.json5"], // Specify the extension or pattern you want to parse as JSON.
    languageOptions: {
      parser: jsoncParser, // Set this parser.
    }
  },
];

📖 Usage (Legacy Config)

In your ESLint configuration file, set the overrides > parser property:

{
  // ...
  // Add the following settings.
  "overrides": [
    {
      "files": ["*.json", "*.json5"], // Specify the extension or pattern you want to parse as JSON.
      "parser": "jsonc-eslint-parser", // Set this parser.
    },
  ],
}

⚙️ Configuration

The following additional configuration options are available by specifying them in parserOptions in your ESLint configuration file.

{
  // Additional configuration options
  "parserOptions": {
    "jsonSyntax": "JSON5"
  }
}

parserOptions.jsonSyntax

Set to "JSON", "JSONC" or "JSON5". Select the JSON syntax you are using.
If not specified, all syntaxes that express static values ​​are accepted. For example, template literals without interpolation.

Note : Recommended to loosen the syntax checking by the parser and use check rules of eslint-plugin-jsonc to automatically fix it.

⚙️ API

parseJSON(code, options?)

Parses the given JSON source code and returns the AST.

import { parseJSON } from "jsonc-eslint-parser";

const ast = parseJSON('{"key": "value"}', { jsonSyntax: "JSON" });
console.log(ast);

Parameters:

• code (string): The JSON source code to parse.
• options (object, optional): Parser options.
  • jsonSyntax ("JSON" | "JSONC" | "JSON5"): The JSON syntax to use.

Returns: JSONProgram - The root AST node.

parseForESLint(code, options?)

Parses the given JSON source code for ESLint. This is the main parser function used by ESLint.

import { parseForESLint } from "jsonc-eslint-parser";

const result = parseForESLint('{"key": "value"}', { jsonSyntax: "JSON" });
console.log(result.ast);
console.log(result.services);
console.log(result.visitorKeys);

Parameters:

• code (string): The JSON source code to parse.
• options (object, optional): Parser options (same as parseJSON).

Returns: An object containing:

• ast: The root AST node.
• services: An object with helper methods like getStaticJSONValue().
• visitorKeys: Visitor keys for traversing the AST.

tokenize(code, options?)

Tokenizes the given JSON source code and returns an array of tokens.

import { tokenize } from "jsonc-eslint-parser";

const tokens = tokenize('{"key": "value"}', { jsonSyntax: "JSON" });
console.log(tokens);
// [
//   { type: 'Punctuator', value: '{', range: [0, 1], loc: {...} },
//   { type: 'String', value: '"key"', range: [1, 6], loc: {...} },
//   { type: 'Punctuator', value: ':', range: [6, 7], loc: {...} },
//   { type: 'String', value: '"value"', range: [8, 15], loc: {...} },
//   { type: 'Punctuator', value: '}', range: [15, 16], loc: {...} }
// ]

// Include comments in the result
const tokensWithComments = tokenize('{"key": "value" /* comment */}', {
  jsonSyntax: "JSONC",
  includeComments: true
});

Parameters:

• code (string): The JSON source code to tokenize.
• options (object, optional): Parser options.
  • jsonSyntax ("JSON" | "JSONC" | "JSON5"): The JSON syntax to use.
  • includeComments (boolean): If true, comments are included in the result array.

Returns: Token[] or (Token | Comment)[] - An array of tokens, optionally including comments.

Usage for Custom Rules / Plugins

• AST.md is AST specification.
• Plugins.md describes using this in an ESLint plugin.
• no-template-literals.ts is an example.
• You can see the AST on the Online DEMO.

🚥 Semantic Versioning Policy

jsonc-eslint-parser follows Semantic Versioning.

👫 Related Packages

• eslint-plugin-jsonc ... ESLint plugin for JSON, JSON with comments (JSONC) and JSON5.
• eslint-plugin-yml ... ESLint plugin for YAML.
• eslint-plugin-toml ... ESLint plugin for TOML.
• eslint-plugin-json-schema-validator ... ESLint plugin that validates data using JSON Schema Validator.
• yaml-eslint-parser ... YAML parser for use with ESLint plugins.
• toml-eslint-parser ... TOML parser for use with ESLint plugins.

🔒 License

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