max-params.md

max-params

Enforce a maximum number of function parameters.

Rule Details

Property	Value
Type	suggestion
Fixable	No
Recommended	warn (max: 4)
Strict	error (max: 4)

Rationale

Functions with many parameters are hard to call correctly, difficult to read, and a sign that the function is doing too much or that related parameters should be grouped into a structured options object. Limiting the parameter count encourages better API design.

Examples

✅ Correct

/**
 * Creates a new user record.
 */
function createUser(options: ICreateUserOptions): Promise<IUser> {
  return db.users.create(options);
}

/**
 * Sends an email notification.
 */
function sendEmail(to: string, subject: string, body: string): Promise<void> {
  return mailer.send({ to, subject, body });
}

❌ Incorrect

function createUser(
  name: string,
  email: string,
  password: string,
  role: string,
  createdAt: Date,
): Promise<IUser> {
  // Too many positional parameters
}

Options

Option	Type	Default	Description
max	number	4	Maximum number of allowed parameters

// Default (max 4)
'zero-tolerance/max-params': 'warn'

// Custom limit
'zero-tolerance/max-params': ['error', { max: 3 }]