Basic MCQs of JavaScript

Basic MCQs of JavaScript

1: Which of the following methods is used to add an element to the end of an array?

• a) push()
• b) pop()
• c) concat()
• d) shift()

a) push()

2: Which of the following is used to declare a variable in JavaScript?

• a) let
• b) var
• c) const
• d) All of the above

d) All of the above

3: What is the correct way to check if a variable x is NOT equal to 5 in JavaScript?

• a) x =! 5
• b) x != 5
• c) x !== 5
• d) x <> 5

c) x !== 5

4: Which built-in method is used to convert a string to lowercase letters?

• a) toLowerCase()
• b) lowerCase()
• c) convertToLower()
• d) changeCaseToLower()

a) toLowerCase()

5: The “typeof” operator in JavaScript is used to:

• a) Check if a variable is of type “undefined”
• b) Determine the type of a variable
• c) Convert a value to a string
• d) Create a new variable

b) Determine …

6: What is the output of the following code?

console.log(2 + “3”);

• a) 23
• b) 5
• c) “23”
• d) 6

c) “23”

7: Which of the following is NOT a valid way to declare a function in JavaScript?

• a) function myFunction() {}
• b) var myFunction = function() {}
• c) const myFunction = () => {}
• d) let myFunction() {}

d) let myFunction() {}

8: The output of the following code will be:

console.log(typeof null);

• a) object
• b) null
• c) undefined
• d) number

a) object

9: The “this” keyword in JavaScript refers to:

• a) The current function
• b) The global object
• c) The object that owns the executing code
• d) The previous object that called the function

c) The object…

10: What is the result of the following expression?

“5” + 2

• a) 7
• b) “7”
• c) “52”
• d) 52

c) “52”

Advance MCQs of JavaScript

11: How can you add a comment in JavaScript?

• a) //This is a comment
• b) <!–This is a comment–>
• c) This is a comment
• d) /This is a comment/

a) //This is a comment

12: Which of the following methods is used to remove the last element from an array in JavaScript?

• a) pop()
• b) push()
• c) shift()
• d) unshift()

a) pop()

13: The “NaN” value in JavaScript stands for:

• a) Not a Null
• b) Not a Number
• c) No Available Number
• d) Null and Negative

b) Not a Number

14: What is the correct way to write a conditional statement in JavaScript?

• a) if (x === 5) { … }
• b) if x = 5 { … }
• c) if x == 5 then { … }
• d) if [x = 5] { … }

a) if (x === 5) { … }

15: Which of the following methods is used to remove the first element from an array in JavaScript?

• a) pop()
• b) push()
• c) shift()
• d) unshift()

c) shift()

16: What is the result of the following expression?

10 % 3

• a) 1
• b) 0
• c) 3.33
• d) 10

a) 1

17: Which of the following is NOT a valid JavaScript data type?

• a) boolean
• b) string
• c) number
• d) character

d) character

18: The “splice()” method in JavaScript is used for:

• a) Sorting an array
• b) Adding elements to an array
• c) Removing elements from an array
• d) Reversing an array

c) Removing elements…

19: What is the output of the following code?

console.log(2 ** 3);

• a) 8
• b) 6
• c) 23
• d) 9

a) 8

20: Which of the following is used to declare a constant variable in JavaScript?

• a) let
• b) var
• c) const
• d) final

c) const

JavaScript Online Quiz with Answers

21: What does the “=== ” operator in JavaScript check for?

• a) Value equality
• b) Type equality
• c) Both value and type equality
• d) None of the above

c) Both value…

22: The output of the following code is:

console.log(Boolean(“”));

• a) true
• b) false
• c) undefined
• d) null

b) false

23: Which of the following is used to loop through the elements of an array in JavaScript?

• a) for loop
• b) while loop
• c) do-while loop
• d) All of the above

d) All of the above

24: The “parseInt()” function in JavaScript is used to:

• a) Convert a string to an integer
• b) Convert a number to a string
• c) Round a number to the nearest integer
• d) Remove decimals from a number

a) Convert a string …

25: What is the correct way to write a JavaScript array?

• a) [1, 2, 3, 4]
• b) (1, 2, 3, 4)
• c) {1, 2, 3, 4}
• d) “1, 2, 3, 4”

a) [1, 2, 3, 4]

26: What is the result of the following expression?

“5” == 5

• a) true
• b) false
• c) undefined
• d) null

a) true

27: Which of the following is NOT a valid JavaScript comparison operator?

• a) ==
• b) !=
• c) <=
• d) ><

d) ><

28: What is the output of the following JavaScript code?

console.log(Math.floor(4.7));

• a) 4
• b) 5
• c) 4.7
• d) 5.3

a) 4

29: Which of the following is NOT a JavaScript framework or library?

• a) React
• b) Angular
• c) Vue
• d) JavaFX

d) JavaFX

30: Which of the following methods is used to convert a string to an array in JavaScript?

• a) split()
• b) join()
• c) slice()
• d) concat()

a) split()

JavaScript Online Test Preparation

31: What is the output of the following code?

console.log(10 > 9 > 8);

• a) true
• b) false
• c) undefined
• d) error

b) false

32: The “querySelector()” method in JavaScript is used to:

• a) Select the first element that matches a specified CSS selector
• b) Add a new CSS class to an element
• c) Change the CSS style of an element
• d) Remove an element from the DOM

Answer: a)

33: What is the output of the following code?

console.log(3 + 2 + “7”);

• a) 12
• b) 327
• c) “57”
• d) 7

c) “57”

34: Which of the following is used to pause the execution of JavaScript code for a specified amount of time?

• a) setTimeout()
• b) setInterval()
• c) clearTimeout()
• d) clearInterval()

a) setTimeout()

35: What does the “return” statement do in a JavaScript function?

• a) Stops the execution of the function and returns a value
• b) Defines a new variable within the function
• c) Prints a message to the console
• d) Loops through an array

a) Stops the execution..