JavaScript Objects & Prototypes - Practice Questions 2026

Master the core of JavaScript development with these comprehensive practice exams. Whether you are preparing for technical interviews or aiming to solidify your understanding of the language’s internal mechanics, these tests provide the rigorous training necessary to excel.

Why Serious Learners Choose These Practice Exams

Serious learners understand that watching tutorials is not enough to master JavaScript. To truly grasp how objects and prototypes function, you must test your knowledge against challenging, edge-case scenarios. These practice exams are designed to bridge the gap between theoretical knowledge and practical application. By engaging with these questions, you develop the muscle memory needed to debug complex inheritance chains and manage object state effectively.

Course Structure

This course is organized into logical tiers to ensure a smooth learning curve, moving from fundamental syntax to complex architectural patterns.

• Basics / Foundations

This section focuses on object literal syntax, property accessors (dot vs. bracket notation), and simple object creation. You will be tested on your ability to define properties and understand the difference between primitive values and reference types.

Here, the focus shifts to the keyword this, constructor functions, and the basic mechanics of the new keyword. Understanding how JavaScript binds context to objects is crucial for any developer.

This module dives deep into Prototypes. You will explore the .prototype property vs. the __proto__ internal link, the prototype chain, and how methods are shared across instances to save memory.

Expect questions on Object. create(), Object. defineProperty(), descriptors (enumerable, writable, configurable), and the nuances of Prototypal Inheritance vs. Class-based syntax.

These questions mimic actual development hurdles, such as deep cloning objects, preventing mutations using Object. freeze() or Object. seal(), and managing data integrity in large applications.

The final sets combine all previous topics into a timed environment. This mimics the pressure of a real technical interview and ensures you can switch context between different object-oriented programming concepts rapidly.

Sample Practice Questions

QUESTION 1

What will be the output of the following code?

JavaScript

function Person(name) {

  this. name = name;

}

Person.prototype.greet = function() {

  return "Hello " + this. name;

};

const user = new Person("Alice");

console. log(user. hasOwnProperty("greet"));

• OPTION 1: true

CORRECT ANSWER: OPTION 2

CORRECT ANSWER EXPLANATION:

The hasOwnProperty method checks if a property exists directly on the object instance itself. In this case, "greet" is defined on Person. prototype, not on the "user" instance. Therefore, while "user.greet()" would work via the prototype chain, the property is not "own," resulting in false.

WRONG ANSWERS EXPLANATION:

• OPTION 1: Incorrect because "greet" is an inherited property, not an own property of the instance.

QUESTION 2

Which method is used to create a new object, using an existing object as the prototype of the newly created object?

• OPTION 1: Object. assign()

CORRECT ANSWER: OPTION 3

CORRECT ANSWER EXPLANATION:

Object. create(proto) is the standard method for creating a new object and explicitly setting its internal [[Prototype]] (proto) to the object provided in the argument.

WRONG ANSWERS EXPLANATION:

• OPTION 1: Object. assign() copies properties from one or more source objects to a target object but does not set the prototype chain.

What is Included in This Course

Welcome to the best practice exams to help you prepare for your JavaScript Objects & Prototypes.

• You can retake the exams as many times as you want to ensure total mastery.

We hope that by now you are convinced! And there are a lot more questions inside the course.