eslint-plugin-optional-params

A ESLint plugin that allows you to limit the number of optional params a function may have. Works with:

• function declarations
• function expressions
• arrow functions
• class methods
• class properties (class methods declared as arrow functions)
• function type declarations
• function declarations within interfaces
• arrow function declarations within interfaces
• abstract methods
• abstract properties (abstract methods declared as arrow functions)

Installation

npm i -D eslint-plugin-optional-params

Rules

• max-optional-params: controls the count of optional params a function may have.
  • Example:

    // 'optional-params/max-optional-params': ['error', 1]
    
    // ❌
    // Only 1 optional param(s) are allowed (eslint)
    function buildMech(head: Head, core: Core, arms?: Arm[], legs?: Leg[]): Mech
    
    // ✅
    // A fix
    function buildMech(params: { head: Head, core: Core, arms?: Arm[], legs?: Leg[] }): Mech

  • When to use it:
    The rule must be used if multiple optional params are dissatisfactory.
    To pass a succeeding optional param a redundant undefined value should be passed as an argument for the preceding param.

Usage

• The plugin must be added to the plugins array in a .eslintrc.* config.
• the eslint-plugin part of the name can be omitted.

// .eslintrc.js
module.exports = {
  // ...
  plugins: [/* other plugins */, 'optional-params']
  rules: {
    // ...
    'optional-params/max-optional-params': ['error', 2],
  }
  // ...
}