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 Array chain Function chain Class chain

Question 2

What are generators in JavaScript?

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

Question 3

What is the Proxy object?

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

Question 4

What are Web Workers?

Run JavaScript in background threads UI threads Main thread Event loop

Question 5

What is the difference between shallow copy and deep copy?

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

Question 6

What is memoization?

Caching function results to improve performance Memory leak Function composition Recursion

Question 7

What is the event delegation pattern?

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

Question 8

What are symbols in JavaScript?

Unique and immutable primitive values Objects Strings Numbers

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 All same bind is immediate apply is for arrays only

Question 10

What is the "new" operator doing?

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

Question 11

What are WeakMap and WeakSet?

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

Question 12

What is currying in JavaScript?

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

Question 13

What is the observer pattern?

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

Question 14

How does the JavaScript engine handle memory management?

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

Question 15

What are JavaScript iterators?

Objects that define a sequence and a next() method Loops Arrays 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 Null check Ternary operator Logical OR

Question 18

What are decorators in JavaScript (proposal)?

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

Question 19

What is a Service Worker?

Script that runs in background for offline support and push notifications Web worker 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 Data pattern Singleton