Javascript MCQs With Answers (JavaScript Online Quiz)
In this part of computer science MCQs, you will find unique and fresh Javascript MCQs With Answers for JavaScript online test preparation. We have collected the most important and repeated MCQs of JavaScript language for your exams and competitive test preparation. These solved MCQs will also help you in JavaScript online Quiz.
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..
Conclusion
I hope you have enjoyed these solved Javascript MCQs With Answers. If you need more Computer Science MCQs with Answers, you can check them below.
More Computer Science MCQs
Computer Network MCQs | For Online Test Preparation
Computer MCQs for Junior Clerk Test Online Preparation
