max-parameters

Report a function that takes more than max parameters. A long positional parameter list is easy to call with arguments in the wrong order.

This rule is part of eslint-plugin-maintainability.

Quick SummaryCopy Anchor Link

Rule DetailsCopy Anchor Link

The rule counts the parameters a caller passes and reports a function with more than max (default 4). Every function form is checked: a declaration, a function expression, an arrow, a class method, a constructor, and an arrow-function class property.

• A rest parameter (...rest) is one parameter.
• A destructured parameter ({ a, b }) is one parameter.
• TypeScript's this parameter is not counted: it is erased before emit and no caller passes it (as in @typescript-eslint/max-params).
• A file whose leading comment declares it generated (@generated) is skipped: a generated signature's arity is the generator's decision.

ConfigurationCopy Anchor Link

With ignoreConstructors, a function declaration whose name starts with an uppercase letter (an ES5 constructor function) is skipped as well.

ExamplesCopy Anchor Link

❌ IncorrectCopy Anchor Link

function createUser(name: string, email: string, age: number, role: Role, team: Team) {}

class Cart {
  total = (a: number, b: number, c: number, d: number, e: number) => a + b + c + d + e;
}

✅ CorrectCopy Anchor Link

function createUser({ name, email, age, role, team }: NewUser) {}

// `this` is not a parameter a caller passes
function onClick(this: HTMLElement, a: number, b: number, c: number, d: number) {}

// With { ignoreOverriddenMethods: true }
class Admin extends User {
  override update(a: string, b: string, c: string, d: string, e: string) {}
}

Configuration ExamplesCopy Anchor Link

// eslint.config.mjs
export default [
  {
    rules: {
      'maintainability/max-parameters': ['error', { max: 5, ignoreConstructors: true }],
    },
  },
];

Related RulesCopy Anchor Link

• cognitive-complexity - Function complexity limits

Further ReadingCopy Anchor Link

• SonarQube RSPEC-107 - Functions should not have too many parameters
• Introduce Parameter Object - The refactoring this rule suggests

Known False NegativesCopy Anchor Link

Overload and declaration signaturesCopy Anchor Link

Why: the rule checks function implementations. A declare function signature, an overload signature or a function type has no body to refactor.

// ❌ NOT DETECTED
declare function legacy(a: number, b: number, c: number, d: number, e: number): void;

Use this rule

npm install -D oxlint-plugin-maintainability

{  "jsPlugins": ["oxlint-plugin-maintainability"],  "rules": {    "maintainability/max-parameters": "error"  }}

import { defineConfig } from 'vite-plus';export default defineConfig({  lint: {    jsPlugins: ['oxlint-plugin-maintainability'],    rules: {      'maintainability/max-parameters': 'error',    },  },});