Introduction
Are you preparing for a JavaScript interview? Do you want to stand out from other candidates by showcasing your understanding of OOPs (Object-Oriented Programming) concepts? In this article, we will explore 10 critical OOPs questions commonly asked during JavaScript interviews. These questions will not only help you assess your knowledge of OOPs concepts but also highlight common mistakes and best practices.
1. What is Object-Oriented Programming?
Object-Oriented Programming (OOP) is a programming paradigm that organizes software design around objects. It involves the use of objects, classes, and their relationships to solve complex problems.
Example:
// Creating a class
class Car {
constructor(make, model) {
this.make = make;
this.model = model;
}
// Method
startEngine() {
console.log('Engine started!');
}
}
// Creating an instance of the Car class
const myCar = new Car('Toyota', 'Camry');
console.log(myCar.make); // Output: Toyota
myCar.startEngine(); // Output: Engine started!
2. What are the Four Pillars of OOP?
The four pillars of OOP are:
- Encapsulation: The bundling of data and methods together within a class.
- Inheritance: The mechanism by which one class acquires the properties and behaviors of another class.
- Polymorphism: The ability of an object to take on many forms.
- Abstraction: The process of hiding complex details and providing a simpler interface.
Example:
// Encapsulation
class BankAccount {
constructor(accountNumber, balance) {
this.accountNumber = accountNumber;
this.balance = balance;
}
// Method to deposit money
deposit(amount) {
this.balance += amount;
}
// Method to withdraw money
withdraw(amount) {
this.balance -= amount;
}
}
// Inheritance
class SavingsAccount extends BankAccount {
// Additional methods specific to SavingsAccount
calculateInterest(rate) {
// Calculate interest
}
}
// Polymorphism
function printBalance(account) {
console.log(account.balance);
}
const myAccount = new SavingsAccount('123456', 1000);
// Abstraction
printBalance(myAccount); // Output: 1000
3. What is the difference between a class and an object?
A class is a blueprint or a template for creating objects, whereas an object is an instance of that class.
Example:
// Class
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
// Method
greet() {
console.log(`Hello, my name is ${this.name}`);
}
}
// Object
const person1 = new Person('John', 30);
console.log(person1.age); // Output: 30
person1.greet(); // Output: Hello, my name is John
4. What is the role of the ‘this’ keyword in JavaScript?
The ‘this’ keyword refers to the context in which a function is called. It allows access to the object’s properties and methods within the function.
Example:
// Object
const person = {
name: 'John',
age: 30,
greet: function() {
console.log(`Hello, my name is ${this.name}`);
}
};
person.greet(); // Output: Hello, my name is John
Stay tuned for the next set of critical OOPs questions!
Remember, preparation is the key to success in interviews. By familiarizing yourself with these critical OOPs questions and their answers, you’ll be better equipped to demonstrate your expertise in JavaScript and impress interviewers.
Conclusion
Improving your understanding of OOPs concepts and preparing for critical OOPs questions can greatly enhance your chances of success in JavaScript interviews. Use the examples provided in this article to practice and reinforce your knowledge. Remember to focus on the four pillars of OOPs and understand how they apply to JavaScript.
Tags: JavaScript, interviews, OOPs, coding, problem-solving, programming
