Quizzes – EduHub

Question 1

What is the prototype chain and how does it work?

Objects inherit from other objects; when property not found, lookup goes up the chain Function chain Array chain Class chain

Question 2

What are generators in JavaScript?

Functions that can be paused and resumed with yield Promises Callbacks Async functions

Question 3

What is the Proxy object?

Event proxy Creates a wrapper to intercept operations on an object Server proxy Network proxy

Question 4

What are Web Workers?

Run JavaScript in background threads UI threads Event loop Main thread

Question 5

What is the difference between shallow copy and deep copy?

Shallow is slower Deep copies references Same Shallow copies only top-level, deep copies all nested objects

Question 6

What is memoization?

Caching function results to improve performance Memory leak Function composition Recursion

Question 7

What is the event delegation pattern?

Event bubbling Event capturing Using parent element to handle events on children Event listeners

Question 8

What are symbols in JavaScript?

Numbers Objects Strings Unique and immutable primitive values

Question 9

What is the difference between call, apply, and bind?

apply is for arrays only bind is immediate call/apply invoke immediately with given this and arguments; bind returns a new function All same

Question 10

What is the "new" operator doing?

Creates a new object, sets prototype, binds this, returns object Declares variable Creates array Calls function

Question 11

What are WeakMap and WeakSet?

Regular Map/Set Arrays Strong collections Collections with weak references (no prevention of GC)

Question 12

What is currying in JavaScript?

Transforming a function with multiple args into sequence of functions with single args Partial application Higher-order function Spicy function

Question 13

What is the observer pattern?

Singleton One-to-many dependency where objects notify observers of changes Factory Module

Question 14

How does the JavaScript engine handle memory management?

Automatic garbage collection using mark-and-sweep Reference counting only No management Manual free

Question 15

What are JavaScript iterators?

Objects that define a sequence and a next() method Arrays Loops Functions

Question 16

What is the difference between deep freeze and Object.freeze?

Object.freeze is shallow, deep freeze recursively freezes Same Deep freeze is built-in Object.freeze is deep

Question 17

What is the "optional chaining" operator (?.)?

Safely access nested properties without checking each level Logical OR Ternary operator Null check

Question 18

What are decorators in JavaScript (proposal)?

React only Experimental feature to modify class behavior declaratively Production feature Typescript only

Question 19

What is a Service Worker?

Web worker Main thread script Script that runs in background for offline support and push notifications Event handler

Question 20

What is the "composite" pattern in JavaScript?

Data pattern UI pattern Singleton Compose objects into tree structures to represent part-whole hierarchies