JavaScript Web Programming Quiz

1. Which method removes the last element from an array?

Shift()

Pop()

Slice()

Splice()

2. What does Object.keys() return?

An array of object values

An array of object property names

The number of properties

A copy of the object

3. Which keyword is used to exit a loop prematurely?

Exit

Stop

Break

Return

4. What is the difference between '==' and '===' in JavaScript?

No difference; they are identical

'==' compares values; '===' compares values and types

'===' is faster than '=='

'==' is for objects; '===' is for primitives

5. Which method converts a string to an integer in JavaScript?

ToInteger()

ParseInt()

Int()

StringToInt()

6. What is the purpose of the 'fetch' API?

Manipulate DOM elements

Make HTTP requests

Create new variables

Define CSS styles

7. Which CSS selector targets elements with a specific class?

#classname

.classname

[classname]

Classname

8. What does the 'finally' block do in a try-catch statement?

Executes only if an error occurs

Executes only if no error occurs

Always executes regardless of error

Skips the catch block

9. Which method is used to filter array elements?

Map()

Filter()

Reduce()

ForEach()

10. What is the correct syntax for a callback function in JavaScript?

Function callback() { }

Callback: function() { }

Both A and B

None of the above

11. Which keyword declares a block-scoped variable in JavaScript?

Var

Let

Const

Declare

12. What is the purpose of the spread operator (...) in JavaScript?

Create a comment

Expand iterables into individual elements

Define a constant

Loop through an array

13. Which event fires when the DOM is fully loaded?

Load

DOMContentLoaded

Ready

Onload

14. What does JSON.stringify() convert?

A string to a JSON object

A JavaScript object to a JSON string

A JSON string to an array

An array to a single string

15. Which method adds one or more elements to the end of an array?

Shift()

Unshift()

Push()

Pop()

16. What is the output of typeof undefined?

"null"

"undefined"

"object"

Null

17. Which of these is a valid way to create an arrow function?

Const fn = => { return 5; }

Const fn = () => { return 5; }

Const fn = function => { return 5; }

Const fn = arrow() => 5

18. What does the 'async' keyword do in a function declaration?

Makes the function run in parallel

Enables the use of 'await' inside the function

Automatically returns a promise

All of the above

19. Which method is used to select an HTML element by its ID?

QuerySelector()

GetElementById()

GetElementByClass()

SelectElement()

20. What is the primary purpose of the 'this' keyword in JavaScript?

Reference the global window object

Reference the current object context

Define a new variable

Create a loop iterator

W3Schools JavaScript Web Programming Quiz