max-params.md

Pattern: Excessive parameter count in function

Issue: -

Description

Functions with many parameters are difficult to read, maintain, and call correctly. When a function has too many parameters, it often indicates that it should be restructured, possibly by grouping related parameters into objects or breaking the function into smaller, more focused functions.

Examples

Example of incorrect code with max 3 parameters:

// Too many parameters
function createUser(name: string, age: number, email: string, address: string) {
  // ...
}

// Arrow function with too many parameters
const processData = (id: number, data: string, type: string, validate: boolean) => {
  // ...
};

class Form {
  // Method with too many parameters
  submit(data: FormData, token: string, userId: string, timestamp: number) {
    // ...
  }
}

Example of correct code:

// Using an options object
interface UserOptions {
  name: string;
  age: number;
  email: string;
  address: string;
}

function createUser(options: UserOptions) {
  // ...
}

// Within parameter limit
function processItem(id: number, data: string, type: string) {
  // ...
}

// Using class structure to reduce parameters
class Form {
  private token: string;
  private userId: string;

  submit(data: FormData) {
    // ...
  }
}

// this parameter doesn't count when configured
function setup(this: void, a: string, b: string, c: string) {
  // ...
}