@lint-suite/eslint-plugin-chain-fits-line

This ESLint plugin keeps TypeScript and JavaScript member-call chains compact by requiring every call property in a chain to remain on one physical source line. It helps make long fluent chains explicit: keep the chain together or name an intermediate result.

Compatibility

Requires ESLint ^10.9.1 and TypeScript >=6.0.3. The package is built and tested with Node.js 24.

Installation

pnpm add -D @lint-suite/eslint-plugin-chain-fits-line eslint@^10.9.1 typescript@^6.0.3 typescript-eslint@^8.69.0

Configuration

The plugin does not configure a parser. This flat config parses the TypeScript examples below:

import plugin from '@lint-suite/eslint-plugin-chain-fits-line';
import tseslint from 'typescript-eslint';

export default [
  {
    files: ['**/*.ts'],
    languageOptions: { parser: tseslint.parser },
    plugins: { 'chain-fits-line': plugin },
    rules: { 'chain-fits-line/chain-fits-line': 'error' }
  }
];

Options

This rule has no options and no line-width setting. It compares the physical source lines of call property names, so reformatting an example can change whether it is reported.

Examples

Each example is checked by this rule alone, not by an entire ESLint suite.

Valid examples

1. Two calls on one line

service.prepare().run();

2. Three calls on one line

request.withToken().send().json();

3. A single member call spread across lines

items
  .map((item) => item.id);

4. A member-access prefix split before a compact chain

client
  .session.prepare().run();

5. A multi-line callback argument on one member call

items.map((item) => {
  return item.id;
});

Invalid examples

1. Two-call chain split before the final call

service.prepare()
  .run();

2. Each call property on a separate line

request
  .withToken()
  .send();

3. Three-call chain split once

pipeline.start().transform()
  .finish();

4. Chain split after a compact first call

store.select()
  .filter(Boolean)
  .map(render);

5. Nested member-call chain split across lines

client.api.create()
  .execute();

The rule reports only member-call chains with at least two calls when their property names span lines. It does not report a single member call split across lines.