eslintconfigjs

eslintconfigjs refers to a JavaScript-based configuration used by ESLint to define linting rules, environments, and parsing behavior. In practice, ESLint configurations are implemented in JavaScript files such as eslint.config.js or .eslintrc.js, and eslintconfigjs is a way to describe configurations authored in JavaScript rather than JSON or YAML. A configuration file typically exports a configuration object from the module, using CommonJS or ESM syntax.

A standard eslintconfigjs may include several core fields:

- env: environments the code is intended to run in (for example browser, node, es2021).

- extends: shared configurations or style guides to extend.

- plugins: additional ESLint plugins to activate.

- parser: a custom parser, often for TypeScript or experimental syntax.

- parserOptions: options for the parser, such as ecmaVersion and sourceType.

- rules: a set of rule overrides and their severity.

- settings: plugin-specific or framework-specific settings.

- overrides: file pattern based overrides to apply different rules or parsers.

Discovery and usage: ESLint looks for configuration files at the project root and up the directory tree, or they can be specified explicitly with a command line option like --config. The eslintconfigjs approach enables dynamic configuration logic, such as conditionally enabling rules based on environment variables or reading additional settings from other files.

Example: a simple CommonJS export might be module.exports = { env: { browser: true, node: true }, extends: ['eslint:recommended'], rules: { 'no-console': 'warn' } }. eslintconfigjs supports more complex setups, including overrides for TypeScript, React, or test files.