Inheritance is one of the four fundamental OOP concepts. It is the mechanism by which one class acquires the properties and behavior of another class. It allows a class to inherit properties and behavior from another class.

JavaScript supports inheritance through prototype-based inheritance. In prototype-based inheritance, objects can inherit properties and behavior from other objects. Every object in JavaScript has a prototype object that it inherits properties and behavior from.

Example

function Person(name, age) {
  this.name = name;
  this.age = age;
}

Person.prototype.getName = function () {
  return this.name;
};

function Employee(name, age, salary) {
  Person.call(this, name, age);
  this.salary = salary;
}

Employee.prototype = Object.create(Person.prototype);
Employee.prototype.constructor = Employee;

Employee.prototype.getSalary = function () {
  return this.salary;
};

let employee = new Employee("John", 25, 50000);
console.log(employee.name); // John
console.log(employee.age); // 25
console.log(employee.salary); // 50000
console.log(employee.getName()); // John
console.log(employee.getSalary()); // 50000

In the above example, the Person class is the base class, and the Employee class is the derived class. The Employee class inherits properties and behavior from the Person class using prototype-based inheritance.

Conclusion

• Inheritance is the mechanism by which one class acquires the properties and behavior of another class.
• JavaScript supports inheritance through prototype-based inheritance.
• In prototype-based inheritance, objects can inherit properties and behavior from other objects.
• Every object in JavaScript has a prototype object that it inherits properties and behavior from.
• Inheritance allows a class to inherit properties and behavior from another class.
• Inheritance is used to create a hierarchy of classes where one class is a subclass of another class.
• Inheritance is used to reuse code and to create a relationship between classes.