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Javascript Inheritance Call Super Constructor Or Use Prototype Chain

When working with JavaScript, understanding inheritance is crucial for building efficient and reusable code. One common question that arises is whether to call the super constructor or use the prototype chain when setting up inheritance between classes. In this article, we'll explore both approaches and their implications to help you make informed decisions in your code.

First, let's discuss calling the super constructor. When using this method, you explicitly invoke the parent class constructor within the child class constructor. This allows you to initialize the parent class properties before adding any child-specific properties. Here's an example to illustrate this:

Javascript

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

class Dog extends Animal {
  constructor(name, breed) {
    super(name);
    this.breed = breed;
  }
}

In this example, the `Dog` class extends the `Animal` class, and by calling `super(name)` in the `Dog` constructor, we ensure that the `name` property from the parent class is properly initialized before setting the `breed` property specific to the `Dog` class.

On the other hand, utilizing the prototype chain for inheritance involves defining shared methods and properties on the prototype of the parent class. This allows all instances of the child class to access these shared properties efficiently. Here's an example of setting up inheritance using the prototype chain:

Javascript

function Animal(name) {
  this.name = name;
}

Animal.prototype.sound = function() {
  console.log('Animal sound');
};

function Dog(name, breed) {
  Animal.call(this, name);
  this.breed = breed;
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;

In this setup, the `Dog` constructor calls the `Animal` constructor using `Animal.call(this, name)` to inherit the `name` property. Then, by setting `Dog.prototype = Object.create(Animal.prototype)`, we establish the prototype chain linking the `Dog` class to the methods defined in the `Animal` class.

When deciding whether to call the super constructor or use the prototype chain for inheritance in JavaScript, consider the complexity of your classes and the level of customization needed. Calling the super constructor is useful for initializing parent class properties before adding child-specific properties, while the prototype chain is beneficial for sharing methods efficiently across instances.

In conclusion, both approaches to inheritance in JavaScript have their advantages and use cases. By understanding how each method works and their implications, you can choose the most appropriate approach for your specific coding requirements. Remember to consider the design of your classes and how you intend to use them to determine the best approach for your JavaScript projects. Happy coding!

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