OOP in JavaScript (original) (raw)

What is a class in JavaScript?

• A built-in object for working with arrays
• A blueprint for creating objects
• A library for JavaScript functions

What is the purpose of the constructor method in a JavaScript class?

• Creates a new instance of the class
• Sets up properties for the class object

How do you create an instance of a class in JavaScript?

JavaScript `

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

`

• const p = new Person('Ajay');
• const p = Person('Ajay');
• const p = createInstance(Person, 'Ajay');
• const p = Object.create(Person);

What does the extends keyword do in JavaScript?

• Allows one class to inherit from another class
• Creates a new instance of a class
• Binds a method to a class
• Defines static methods in a class

What is encapsulation in JavaScript OOP?

• Using a constructor to initialize properties
• Inheriting properties from a parent class
• Combining multiple classes into one
• Restricting direct access to object properties and methods

What will the following code log?

JavaScript `

class Animal { makeSound() { console.log("Generic sound"); } } class Dog extends Animal { makeSound() { console.log("Bark"); } } const pet = new Dog(); pet.makeSound();

`

What is polymorphism in OOP?

• A way to define private properties
• Combining classes into a single object
• Using the same method name but with different implementations in child classes
• Sharing methods between unrelated objects

What are static methods in JavaScript classes?

• Methods only accessible to instances of the class
• Methods accessible only on the class itself
• Methods that are inherited by subclasses
• Methods that override the constructor

What will the following code log?

JavaScript `

class Vehicle { static start() { console.log("Starting vehicle..."); } } Vehicle.start();

`

Which of the following best describes inheritance in JavaScript?

• Creating a new class from a string
• Sharing properties and methods between objects of the same type
• Deriving a new class from an existing class to reuse code
• Encapsulating object properties

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