Quizzes – EduHub

Question 1

What is the prototype chain and how does it work?

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

Question 2

What are generators in JavaScript?

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

Question 3

What is the Proxy object?

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

Question 4

What are Web Workers?

Main thread UI threads Run JavaScript in background threads Event loop

Question 5

What is the difference between shallow copy and deep copy?

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

Question 6

What is memoization?

Memory leak Caching function results to improve performance Recursion Function composition

Question 7

What is the event delegation pattern?

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

Question 8

What are symbols in JavaScript?

Unique and immutable primitive values Strings Numbers Objects

Question 9

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

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

Question 10

What is the "new" operator doing?

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

Question 11

What are WeakMap and WeakSet?

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

Question 12

What is currying in JavaScript?

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

Question 13

What is the observer pattern?

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

Question 14

How does the JavaScript engine handle memory management?

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

Question 15

What are JavaScript iterators?

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

Question 16

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

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

Question 17

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

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

Question 18

What are decorators in JavaScript (proposal)?

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

Question 19

What is a Service Worker?

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

Question 20

What is the "composite" pattern in JavaScript?

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