ContextQMD
Back to Flow

flow-eslint

packages/flow-eslint/README.md

0.323.02.5 KB
Original Source

flow-eslint

flow-eslint is a custom parser for ESLint. It is the recommended parser for use for linting with Flow code.

Usage

Flat config (eslint.config.js)

To use flow-eslint with ESLint flat config, set it as languageOptions.parser:

js
module.exports = [
  {
    languageOptions: {
      parser: require('flow-eslint'),
    },
  },
];

You can configure parser options with languageOptions.parserOptions:

js
module.exports = [
  {
    languageOptions: {
      parser: require('flow-eslint'),
      parserOptions: {
        sourceType: 'module',
      },
    },
  },
];

Legacy config (.eslintrc)

If you are still using legacy ESLint config, specify "flow-eslint" as the "parser" in your .eslintrc file:

json
{
  "parser": "flow-eslint"
}

The ESLint documentation provides more information about how to configure ESLint, including how to specify a custom parser.

Options

You may provide additional configuration for flow-eslint by passing an object containing configuration options as parserOptions in your ESLint configuration file. In flat config, this is languageOptions.parserOptions. This object may contain the following properties:

ts
type ParserOptions = {
  /**
   * The identifier that's used for JSX Element creation (after transpilation).
   * This should not be a member expression - just the root identifier (i.e. use "React" instead of "React.createElement").
   *
   * To use the new global JSX transform function, you can explicitly set this to `null`.
   *
   * Defaults to `"React"`.
   */
  jsxPragma?: string | null,

  /**
   * The identifier that's used for JSX fragment elements (after transpilation).
   * If `null`, assumes transpilation will always use a member on `jsxFactory` (i.e. React.Fragment).
   * This should not be a member expression - just the root identifier (i.e. use "h" instead of "h.Fragment").
   *
   * Defaults to `null`.
   */
  jsxFragmentName?: string | null,

  /**
   * The source type of the script.
   *
   * Defaults to `"module"`.
   */
  sourceType?: 'script' | 'module',

  /**
   * Ignore <fbt /> JSX elements when adding references to the module-level `React` variable.
   * FBT is JSX that's transformed to non-JSX and thus references differently
   *
   * https://facebook.github.io/fbt/
   */
  fbt?: boolean,
};
json
{
  "parser": "flow-eslint",
  "parserOptions": {
    "sourceType": "module"
  }
}