JavaScript Class: Basics (ক্লাস)

class Student {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }

  introduce() {
    return `আমি ${this.name}, বয়স ${this.age}`;
  }
}

const s1 = new Student("আনামুল", 22);
const s2 = new Student("প্রিয়াঞ্জলী", 20);

console.log(s1.name); // আনামুল
console.log(s2.introduce()); // আমি প্রিয়াঞ্জলী, বয়স 20

class Product {
  constructor(name, price, discount = 0) {
    this.name = name;
    this.price = price;
    this.discount = discount;
  }
}

const laptop = new Product("ল্যাপটপ", 65000);
const phone = new Product("মোবাইল", 15000, 500);

console.log(laptop.price); // 65000
console.log(phone.discount); // 500

class Counter {
  constructor(step = 1) {
    this.value = 0;
    this.step = step;
  }

  add() {
    this.value += this.step;
  }

  show() {
    return this.value;
  }
}

const counter = new Counter(2);
counter.add();
counter.add();
console.log(counter.show()); // 4

const s1 = new Student("আনামুল", 22);

s1.age = 23;              // বদলানো
s1.city = "ঢাকা";          // নতুন যোগ

delete s1.city;            // মুছে ফেলা
console.log(s1.city);      // undefined
console.log(s1.age);       // 23

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

const p1 = new Person("আনামুল");
const p2 = new Person("প্রিয়াঞ্জলী");

console.log(p1 === p2); // false — আলাদা object
console.log(p1 instanceof Person); // true
console.log(p2 instanceof Object); // true