What is SOLID Principles of Object-oriented Programming?

The SOLID principles are a set of guidelines that were introduced by software engineer Robert C. Martin to help developers design maintainable and scalable object-oriented software. The SOLID principles are as follows:

Single Responsibility Principle (SRP): A class should have only one reason to change. This means that a class should have a single, well-defined responsibility, and that responsibility should be encapsulated by the class.

Here is an example of Single Responsibility Principle:

class Employee {
  constructor(name, address, salary) {
    this.name = name;
    this.address = address;
    this.salary = salary;
  }
  getPay() {
    // Calculate and return the employee's pay
  }
}
class PayStubSender {
  constructor(employee) {
    this.employee = employee;
  }
  sendPayStub() {
    // Send the employee their pay stub
  }
}
const employee = new Employee('John Smith', '123 Main St', 50000);
const payStubSender = new PayStubSender(employee);
payStubSender.sendPayStub();

In this example, the Employee class has a single responsibility: storing information about an employee and calculating their pay. The PayStubSender class has a separate responsibility: sending the employee their pay stub. This ensures that the Employee class is only concerned with its own responsibilities and is not cluttered with unrelated code.

Open-Closed Principle (OCP): Software entities (classes, modules, functions, etc.) should be open…