Quizzes – EduHub

Question 1

What is the prototype chain and how does it work?

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

Question 2

What are generators in JavaScript?

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

Question 3

What is the Proxy object?

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

Question 4

What are Web Workers?

Main thread Run JavaScript in background threads Event loop UI threads

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?

Recursion Function composition Caching function results to improve performance Memory leak

Question 7

What is the event delegation pattern?

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

Question 8

What are symbols in JavaScript?

Numbers Strings Unique and immutable primitive values Objects

Question 9

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

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

Question 10

What is the "new" operator doing?

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

Question 11

What are WeakMap and WeakSet?

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

Question 12

What is currying in JavaScript?

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

Question 13

What is the observer pattern?

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

Question 14

How does the JavaScript engine handle memory management?

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

Question 15

What are JavaScript iterators?

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

Question 16

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

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

Question 17

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

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

Question 18

What are decorators in JavaScript (proposal)?

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

Question 19

What is a Service Worker?

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

Question 20

What is the "composite" pattern in JavaScript?

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