How Well Do You Know JavaScript? Take the Ultimate Quiz!

Gensen Huang

Created 6/20/2024

64.94%

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Sources

https://andersonguelphjs.github.io/OReilly_JavaScript_The_Good_Parts_May_2008.pdf

Test your knowledge of JavaScript with this challenging quiz! How many correct answers can you get out of 20?

1. Which of the following is true about 'typeof' operator in JavaScript?

It always returns an accurate type

It can return incorrect types like 'object' for null

It only works with primitive types

It is not a part of JavaScript

2. What is the role of Function.prototype.method in JavaScript?

To create a new method

To define new methods on function prototypes

To call methods

To delete a method

3. What does the void operator return in JavaScript?

null

undefined

false

4. What is required before a regular expression literal to avoid ambiguity in JavaScript?

A number

Whitespace

A ( or = or : or , character

A letter

5. What is the purpose of the 'use strict' directive in JavaScript?

It enables automatic error correction in the code

It allows the use of older, deprecated JavaScript features

It enforces stricter parsing and error handling in your JavaScript code

It enhances the performance of JavaScript by optimizing the execution process

6. Which statement about functions in JavaScript is true?

Functions cannot be nested

Functions are hoisted if declared with the 'var' keyword

Functions are values

Functions do not have access to their own scope

7. How do you declare a function expression in JavaScript?

function foo() {}

var foo = function() {}

foo = () => {}

var foo = new Function()

8. Why is the use of == operator discouraged in JavaScript?

It is slower than ===

It only compares objects

It attempts to coerce the values, leading to unexpected results

It is an old feature

9. Which form hides the true nature of JavaScript by mimicking class inheritance?

Functional form

Pseudoclassical form

Object specifiers

Prototypal form

10. What is a closure in JavaScript?

A type of array

An object

A function within another function with access to the outer scope

A regular expression

11. Which operator is overloaded in JavaScript's regular expression literals?

12. Which statement is true about JavaScript arrays?

They are primitive types

They are immutable

They are objects

They cannot be nested

13. Which of the following is true about JavaScript objects?

They must have a fixed structure

They are mutable

They do not support inheritance

They are class-bound

14. What is eval mainly used for in JavaScript?

Running JavaScript code strings

Creating objects

Accessing variables

Handling arrays

15. In Simplified JavaScript, what are functions described as?

First-class objects

Second-class objects

Primitive types

Utility types

16. The use of global variables in JavaScript:

Improves code transparency

Complicates behavior

Facilitates modular coding

Enhances functionality

17. What does the term 'hoisting' refer to in JavaScript?

Automatically moving declarations to the top of their scope

Converting primitives to objects

Graceful error handling

Inheriting methods from prototypes

18. Which JavaScript feature always returns undefined?

Null

Void

Eval

NaN

19. What is the recommended way to handle long parameter lists for constructors in JavaScript?

Using multiple constructors

Using an array

Using an object specifier

Using default parameters

20. What does the prototype chain in JavaScript ensure?

Classes and inheritance

Global variable access

Object property look-up

Immutable object instances

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