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# functional/no-class-inheritance

📝 Disallow inheritance in classes.

💼 This rule is enabled in the following configs: ☑️ `lite`, ![badge-noOtherParadigms](https://img.shields.io/badge/-noOtherParadigms-yellow.svg) `noOtherParadigms`, ✅ `recommended`, 🔒 `strict`.

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Disallow use of inheritance for classes.

## Rule Details

### ❌ Incorrect

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```js
/* 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

```js
/* 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:

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

### Default Options

```ts
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.