JavaScript Prototypal Inheritance vs Class-Based Inheritance

There are two main models for inheritance in JavaScript- prototypical inheritance and class-based inheritance (introduced in ES6). 

comparison between them are as given below,

Prototypal Inheritance

Objects in JavaScript inherit through prototype chains, enabling dynamic object behavior and programming.

Prototype Chain
Every object in JavaScript has an internal property called [[Prototype]] (usually accessed via __proto__ or Object.getPrototypeOf()). When you access a property or method on an object, JavaScript checks the object itself first. If no property or method is found, it searches at the object's prototype (its [[Instance]]), and continues up the chain until it finds it or reaches the end (where the instance is null).

Constructor Functions
Objects are created through constructor functions or directly with object literals ({}). In a traditional object-oriented framework, constructors and functions can be thought of as classes, but they are primarily used to define and initialize objects and their instances

Inheritance
Inheritance is achieved by inserting a pattern of an object into another object. This can be done with Object.create() or by directly modifying the __proto__ property (although this is not recommended for production code due to potential performance and compatibility issues).

Example- 

// Constructor function
function Animal(name) {
   this.name = name;
}
// Adding method to prototype
Animal.prototype.makeSound = function() {
   console.log('Animal sound');
};
// Creating instances
let dog = new Animal('Dog');
dog.makeSound(); // Outputs: Animal sound

Class-Based Inheritance (ES6 and later)

ES6 provides classes for defining and extending objects in JavaScript, simplifying inheritance management.

Class Syntax

Classes introduced in ES6 provide a familiar syntax for defining and inheriting objects, similar to languages ​​like Java or C++. Under the hood, classes in JavaScript still use prototype inheritance.
 

Constructor and Methods

Courses are declared using the course keyword. They have a constructor method to start with and can have additional methods defined in their bodies.
 

Inheritance

They are inherited using the extends keyword. A subclass inherits from the superclass by using the super keyword to invoke the superclass constructor and the access method.

Example-

// Class syntax
class Animal {
   constructor(name) {
       this.name = name;
   }
   makeSound() {
       console.log('Animal sound');
   }
}
// Subclass
class Dog extends Animal {
   constructor(name) {
       super(name); // Call the superclass constructor
   }
   // Can override methods
   makeSound() {
       console.log('Bark');
   }
}
// Creating instances
let dog = new Dog('Dog');
dog.makeSound(); // Outputs: Bark

Comparison

Syntax- Classes provide a structured and readable way to describe objects and properties, especially for developers familiar with class-based languages.

Underlying Mechanism- Despite syntax differences, JavaScript relies on prototype inheritance and class-based inheritance and ultimately prototype chaining

Flexibility- Allows for more dynamic processing and runtime flexibility from prototype assets. The classes tend to provide syntactic sugar rather than inheritance but are more rigorous in structure and semantics.

Also, Read: Explain the JavaScript Arrays