Questions

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1What is the constructor function?

2What are Objects?

3What are the properties of an object?

4How does javascript implements object oriented programming?

5What are the key differences between javascript’s Object-based Inheritance and Conventional Class-based Inheritance?

6What is a prototype in JavaScript?

7How we can implement prototype-based inheritance?

8Explain the prototype chain and its role in property lookup.

9What is the difference between an object's `__proto__` and a constructor function's `prototype` property and [[Prototype]]?

10What are object wrappers for primitive type?

11Can you explain the use of object wrappers with examples?

12Explain how the `instanceof` operator works.

13What are different methods to create an object?

14What is an object initializer?

15What does the `Object.create()` method do?

16How are constructor functions used to create objects with shared properties and methods?

17Show an example of ES6 classes to create objects and inherit properties?

18What are factory functions in JavaScript ?

19What are Object constructors in JavaScript ?

20How can you add new properties and methods to the prototype of an existing constructor function?

21What is prototype pollution, and how can it be a security risk in JavaScript?

22Is modifying or extending built-in object prototypes recommended (e.g., adding a method to `Array.prototype`)? Why or why not?

23What happens when you try to access a property that doesn't exist on an object?

24How can you prevent or mitigate prototype pollution vulnerabilities in your code?

25How does the `Object.prototype.hasOwnProperty()` method work?

26How can you optimize prototype chain lookup for better performance?

27Can you explain how `Object.prototype.constructor` property works?

28What is the difference between modifying the prototype of an object and adding a property directly to the object?

29How does JavaScript handle circular references in object prototypes?

30What is static dispatching in object-oriented programming?

31What is the purpose of the `Object.keys()` method?

32Write a function flattenObject(obj) that flattens a deeply nested object into a single-level object, using dot notation for nested keys.

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What are object wrappers for primitive type?

object wrappers are objects that encapsulate primitive data types (such as numbers, strings, and booleans) and provide them with additional methods and properties. These wrappers allow you to treat primitive values as objects, enabling you to access and manipulate their values more conveniently. All primitive types, except null and undefined, have their corresponding object wrapper types,

The 'Autoboxing' Process

1
When you try to access a property or method on a primitive, JavaScript temporarily wraps that primitive in a special object so you can use its powers.
2
The Trigger: You call .toUpperCase() on a string.
3
The Wrap: JavaScript creates a temporary String object: new String('gemini').
4
The Execution: It runs the method on that object and returns the result.
5
The Cleanup: JavaScript immediately throws the object away (garbage collection) to save memory.

Why not just use Objects for everything?

1
Performance: Objects are heavy. Primitives are 'passed by value' and stored directly on the Stack. Primitives are lightning-fast and memory efficient.
2
Objects are stored on the Heap, require memory addresses (pointers), and consume more resources.
3
By using wrappers, JavaScript gives you the speed of primitives with the functionality of objects only when you actually need it.

A common mistake is trying to assign a property to a primitive. It won't throw an error (in non-strict mode), but it won't work because of the 'temporary' nature of the wrapper.