@lexical/eslint-plugin weekly downloads statistics

@lexical/eslint-plugin

This ESLint plugin enforces the Lexical $function convention.

ESLint Compatibility: This plugin supports ESLint 9 and later with the flat config format (eslint.config.js). Support for ESLint 7-8 and the legacy .eslintrc format was removed in v0.51.0.

Installation

Assuming you already have ESLint installed, run:

npm install @lexical/eslint-plugin --save-dev

Configuration

Add the recommended config to your eslint.config.js:

import lexical from '@lexical/eslint-plugin';

export default [
  // ... other configs
  lexical.configs.recommended
];

lexical.configs['flat/recommended'] and lexical.configs['flat/all'] are aliases of recommended and all from when those names were the legacy configs.

Custom Configuration

import lexical from '@lexical/eslint-plugin';

export default [
  {
    plugins: {
      '@lexical': lexical
    },
    rules: {
      '@lexical/rules-of-lexical': 'error'
    }
  }
];

Advanced configuration

Most of the heuristics in @lexical/rules-of-lexical can be extended with additional terms or patterns.

The code example below is shown using the default implementations for each option. When you configure these they are combined with the default implementations using "OR", the default implementations can not be overridden. These terms and patterns are only shown for reference and pasting this example into your project is not useful.

If the string begins with a "^" or "(" then it is treated as a RegExp, otherwise it will be an exact match. A string may also be used instead of an array of strings.

import lexical from '@lexical/eslint-plugin';

export default [
  {
    plugins: {
      '@lexical': lexical
    },
    rules: {
      '@lexical/rules-of-lexical': [
        'error',
        {
          isDollarFunction: ['^\\$[a-z_]'],
          isIgnoredFunction: [],
          isLexicalProvider: [
            'parseEditorState',
            'read',
            'registerCommand',
            'registerNodeTransform',
            'update'
          ],
          isSafeDollarFunction: ['^\\$is']
        }
      ]
    }
  }
];

isDollarFunction

Base case: /^\$[a-z_]/

This defines the $function convention, which by default is any function that starts with a dollar sign followed by a lowercase latin letter. You may have a secondary convention in your codebase, such as non-latin letters, or an internal prefix that you want to consider (e.g. "^INTERNAL_\\$").

isIgnoredFunction

Base case: None

Functions that match these patterns are ignored from analysis, they may call Lexical $functions but are not considered to be a dollar function themselves.

isLexicalProvider

Base case: /^(parseEditorState|read|registerCommand|registerNodeTransform|update)$/

These are functions that allow their function argument to use Lexical $functions.

isSafeDollarFunction

Base case: /^\$is/

These $functions are considered safe to call from anywhere, generally these functions are runtime type checks that do not depend on any other state.

Testing

To verify that the plugin works with different ESLint versions, run the integration tests:

pnpm run test-eslint-integration

This will test:

• ✓ ESLint 9 with a flat eslint.config.js configuration
• ✓ ESLint 10 with the same configuration

The tests use pnpm dlx to run different ESLint versions without modifying package.json or pnpm-lock.yaml.

Valid and Invalid Examples

Valid Examples

$functions may be called by other $functions

function $namedCorrectly() {
  return $getRoot();
}

$functions may be called in functions defined when calling the following methods (the heuristic only considers the method name):

• editor.update
• editorState.read
• editor.registerCommand
• editor.registerNodeTransform

function validUsesEditorOrState(editor) {
  editor.update(() => $getRoot());
  editor.getLatestState().read(() => $getRoot());
}

$functions may be called from class methods

class CustomNode extends ElementNode {
  appendText(string) {
    this.appendChild($createTextNode(string));
  }
}

Invalid Examples

Rename autofix

function invalidFunction() {
  return $getRoot();
}
function $callsInvalidFunction() {
  return invalidFunction();
}

Autofix: The function is renamed with a $ prefix. Any references to this name in this module are also always renamed.

function $invalidFunction() {
  return $getRoot();
}
function $callsInvalidFunction() {
  return $invalidFunction();
}

Rename & deprecate autofix

export function exportedInvalidFunction() {
  return $getRoot();
}

Autofix: The exported function is renamed with a $ prefix. The previous name is also exported and marked deprecated, because automatic renaming of references to that name is limited to the module's scope.

export function $exportedInvalidFunction() {
  return $getRoot();
}
/** @deprecated renamed to {@link $exportedInvalidFunction} by @lexical/eslint-plugin rules-of-lexical */
export const exportedInvalidFunction = $exportedInvalidFunction;

Rename scope conflict

import {$getRoot} from 'lexical';
function InvalidComponent() {
  const [editor] = useLexicalComposerContext();
  const getRoot = useCallback(() => $getRoot(), []);
  return (<button onClick={() => editor.update(() => getRoot())} />);
}

Autofix: The function is renamed with a $ prefix and _ suffix since the suggested name was already in scope.

import {$getRoot} from 'lexical';
function InvalidComponent() {
  const [editor] = useLexicalComposerContext();
  const $getRoot_ = useCallback(() => $getRoot(), []);
  return (<button onClick={() => editor.update(() => $getRoot_())} />);
}