Course/Module 5/Topic 1 of 3Intermediate

Classes & OOP - Concepts

Explore the key concepts of classes & oop with practical examples and exercises.

45 min•By Priygop Team•Last updated: Feb 2026

Introduction to Classes & OOP

In this section, we cover the fundamental aspects of classes & oop. You'll learn core concepts, see real-world examples, and understand how to apply them in your projects.

Key Concepts

Understanding the core principles of classes & oop
Practical applications and real-world use cases
Step-by-step implementation guides
Common patterns and best practices
Tips for debugging and troubleshooting
Performance optimization techniques

Classes & OOP - Code Example

Example

// TypeScript Class
class Animal {
  constructor(
    public name: string,
    protected species: string,
    private _age: number
  ) {}
  
  get age(): number { return this._age; }
  set age(value: number) {
    if (value < 0) throw new Error("Age cannot be negative");
    this._age = value;
  }
  
  describe(): string {
    return `${this.name} is a ${this.species}, age ${this._age}`;
  }
}

class Dog extends Animal {
  constructor(name: string, age: number, public breed: string) {
    super(name, "Dog", age);
  }
  bark(): string { return `${this.name} says Woof!`; }
}

Try It Yourself: Classes & OOP

Try It Yourself: Classes & OOPJavaScript⚠ 1 error

⚠ Syntax Issues (1)

Line 1: JS Error: Unexpected strict mode reserved word

💡 Check syntax near the highlighted line.

JavaScript Editor

✕ 1 errorTab = 2 spaces

// Build a simple class hierarchy
class Shape {
  constructor(public color: string) {}
  area(): number { return 0; }
  describe(): string { return `${this.color} shape, area: ${this.area()}`; }
}

class Circle extends Shape {
  constructor(color: string, public radius: number) { super(color); }
  area(): number { return Math.PI * this.radius ** 2; }
}

class Rectangle extends Shape {
  constructor(color: string, public width: number, public height: number) { super(color); }
  area(): number { return this.width * this.height; }
}

const shapes: Shape[] = [new Circle("red", 5), new Rectangle("blue", 4, 6)];
shapes.forEach(s => console.log(s.describe()));

Result

Click ▶ Run to see the result

Edit the code on the left, then click Run

JavaScript|19 lines|661 chars|1 error, 0 warnings

UTF-8

Quick Quiz: Classes & OOP

Chat on WhatsAppPriygop - Leading Professional Development Platform | Expert Courses & Interview Prep