JavaScript MCQs – Object-Oriented Programming

class Animal {  
  constructor(name) {  
    this.name = name;  
  }  
  speak() {  
    return `${this.name} makes a noise.`;  
  }  
}  
class Dog extends Animal {  
  speak() {  
    return `${this.name} barks.`;  
  }  
}  
const dog = new Dog("Rex");  
console.log(dog.speak());

class Alpha {  
  constructor() {  
    this.alpha = "A";  
  }  
}  
class Beta extends Alpha {  
  constructor() {  
    super();  
    this.beta = "B";  
  }  
}  
const obj = new Beta();  
console.log(obj.alpha, obj.beta);

class Example {  
  static greet() { return "Hello!"; }  
}  
console.log(Example.greet());

class Parent {  
  constructor() {  
    this.value = 10;  
  }  
  getValue() {  
    return this.value;  
  }  
}  
class Child extends Parent {  
  constructor() {  
    super();  
    this.value = 20;  
  }  
}  
const child = new Child();  
console.log(child.getValue());

class Example {  
  constructor() {  
    this.data = 42;  
  }  
}  
Example.prototype.data = 100;  
const ex = new Example();  
delete ex.data;  
console.log(ex.data);

class Base {  
  constructor() {  
    this.value = 10;  
  }  
}  
class Derived extends Base {  
  constructor() {  
    super();  
    this.value += 5;  
  }  
}  
const obj = new Derived();  
console.log(obj.value);

class Tool {  
  constructor() {  
    this.name = "tool";  
  }  
  static describe() {  
    return "This is a tool.";  
  }  
}  
const hammer = new Tool();  
console.log(hammer.describe());

function Person(name) {  
  this.name = name;  
}  
Person.prototype.greet = function () {  
  return `Hello, ${this.name}`;  
};  
const person = new Person("Alice");  
console.log(person.greet());

class Counter {  
  constructor() {  
    this.count = 0;  
  }  
  increment() {  
    return ++this.count;  
  }  
}  
const counter1 = new Counter();  
const counter2 = new Counter();  
counter1.increment();  
counter2.increment();  
console.log(counter1.count, counter2.count);

class Example {  
  static logMessage() {  
    console.log("Static method called!");  
  }  
}  
const ex = new Example();  
ex.logMessage();