no-class-inheritance.md

Disallow inheritance in classes (functional/no-class-inheritance)

💼 This rule is enabled in the following configs: ☑️ lite, noOtherParadigms, ✅ recommended, 🔒 strict.

Disallow use of inheritance for classes.

Rule Details

❌ Incorrect

/* eslint functional/no-class-inheritance: "error" */

abstract class Animal  {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

class Dog extends Animal {
  constructor(name, age) {
    super(name, age);
  }

  get ageInDogYears() {
    return 7 * this.age;
  }
}

const dogA = new Dog("Jasper", 2);

console.log(`${dogA.name} is ${dogA.ageInDogYears} in dog years.`);

✅ Correct

/* eslint functional/no-class-inheritance: "error" */

class Animal {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

class Dog {
  constructor(name, age) {
    this.animal = new Animal(name, age);
  }

  get ageInDogYears() {
    return 7 * this.animal.age;
  }
}

console.log(`${dogA.name} is ${getAgeInDogYears(dogA.age)} in dog years.`);

Options

This rule accepts an options object of the following type:

type Options = {
  ignoreIdentifierPattern?: string[] | string;
  ignoreCodePattern?: string[] | string;
};

Default Options

const defaults = {};

ignoreIdentifierPattern

This option takes a RegExp string or an array of RegExp strings. It allows for the ability to ignore violations based on the class's name.

ignoreCodePattern

This option takes a RegExp string or an array of RegExp strings. It allows for the ability to ignore violations based on the code itself.