Answering JavaScript MCQ or JavaScript quiz questions is a great way to prepare for coding interviews, online tests, competitive exams, or just to test your JS skills.
These MCQs cover important concepts such as variables, data types, functions, loops, operators, the DOM, asynchronous programming, ES6 features, and much more.
JavaScript Multiple Choice Questions
JavaScript is one of the most widely used programming languages in the world, especially for web development, and practising JavaScript MCQ questions is a smart way to test your knowledge, revise important topics, and recall fundamental concepts.
Go through each JavaScript quiz, think about the answer, and then click “Show Answer” to check your response.
Q1. What is JavaScript mainly used for on websites?
A. Designing the layout
B. Styling text
C. Adding interaction and dynamic behavior
D. Hosting the website online
Show Answer
Answer: C
Q2. Which JavaScript command is used to show a popup alert message?
A. popup()
B. show()
C. alert()
D. notify()
Show Answer
Answer: C
Q3. Which keyword allows you to declare a variable that can be reassigned later?
A. const
B. let
C. fixed
D. define
Show Answer
Answer: B
Q4. Which of the following is a valid JavaScript variable name?
A. 3name
B. name#
C. _name
D. first-name
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Answer: C
Q5. What data type is used to store true or false values in JavaScript?
A. Number
B. Boolean
C. String
D. LogicalType
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Answer: B
Q6. What does the value ‘undefined’ usually represent in JavaScript?
A. A variable without a value assigned
B. A broken script
C. A false condition
D. A number conversion error
Show Answer
Answer: A
Q7. What will console.log(typeof null) output in JavaScript?
A. ‘null’
B. ‘object’
C. ‘undefined’
D. ‘number’
Show Answer
Answer: B
Q8. JavaScript is considered which type of language?
A. Strongly typed
B. Loosely typed
C. Machine language
D. Assembly language
Show Answer
Answer: B
Q9. Which operator checks both value and data type?
A. ==
B. ===
C. =
D. !==
Show Answer
Answer: B
Q10. What is the output of console.log(5);?
A. ‘5’
B. undefined
C. 5
D. null
Show Answer
Answer: C
Q11. What is JavaScript?
A. A markup language
B. A database language
C. A scripting language used mainly for web browsers
D. A server operating system
Show Answer
Answer: C
Q12. Which statement is used to repeat a block of code a specific number of times?
A. repeat
B. for
C. if
D. check
Show Answer
Answer: B
Q13. What does an if statement do in JavaScript?
A. Declares a constant
B. Runs code only when a condition is true
C. Stops execution
D. Creates a loop
Show Answer
Answer: B
Q14. Which of the following is NOT a loop in JavaScript?
A. for
B. while
C. loop
D. do-while
Show Answer
Answer: C
Q15. Which keyword is commonly used to exit a switch case?
A. stop
B. end
C. break
D. close
Show Answer
Answer: C
Q16. Which operator is known as the “strict equality” operator?
A. =
B. ==
C. ===
D. !=
Show Answer
Answer: C
Q17. Which keyword is used to declare a block-scoped variable?
A. var
B. let
C. define
D. scope
Show Answer
Answer: B
Q18. What is JavaScript most commonly executed by?
A. The web browser
B. The server hardware
C. The database engine
D. The operating system kernel
Show Answer
Answer: A
Q19. Which symbol is used for comments that span only one line?
A. #
B. //
C. —
D. **
Show Answer
Answer: B
Q20. Which of the following describes ECMAScript?
A. A browser
B. The official standard that JavaScript follows
C. A CSS library
D. A database engine
Show Answer
Answer: B
Q21. What is a function in JavaScript?
A. A CSS property
B. A reusable block of code
C. A database query
D. A browser event
Show Answer
Answer: B
Q22. How do you define a function in JavaScript?
A. function myFunc() {}
B. create myFunc() {}
C. define myFunc() {}
D. call myFunc() {}
Show Answer
Answer: A
Q23. What will console.log(4 + 6) output?
A. 10
B. “10”
C. 46
D. undefined
Show Answer
Answer: A
Q24. Which keyword is used to create a constant value in JavaScript?
A. let
B. const
C. var
D. constant
Show Answer
Answer: B
Q25. What is a JavaScript variable?
A. A place to store data values
B. A web server
C. A browser shortcut
D. A CSS effect
Show Answer
Answer: A
Q26. Which function converts a JSON string into a JavaScript object?
A. JSON.stringify()
B. JSON.parse()
C. JSON.convert()
D. JSON.decode()
Show Answer
Answer: B
Q27. What is a closure in JavaScript?
A. A way to delete variables
B. A function with access to its outer scope
C. A security feature
D. A loop structure
Show Answer
Answer: B
Q28. What is hoisting in JavaScript?
A. Removing variables
B. Moving declarations to the top
C. Encrypting code
D. Downloading scripts online
Show Answer
Answer: B
Q29. What is an arrow function?
A. A loop type
B. A shorter way to write functions
C. A DOM element
D. A CSS selector
Show Answer
Answer: B
Q30. What is the purpose of the return statement in a function?
A. To stop the browser
B. To exit the function and send back a value
C. To refresh the page
D. To declare a variable
Show Answer
Answer: B
Q31. What is a JavaScript object?
A. A list of ordered values
B. A collection of key–value pairs
C. A database table
D. A CSS class
Show Answer
Answer: B
Q32. Which symbol is used to access object properties?
A. :
B. .
C. #
D. *
Show Answer
Answer: B
Q33. What does the spread operator (…) do with arrays?
A. Compresses them
B. Expands elements individually
C. Deletes values
D. Sorts values alphabetically
Show Answer
Answer: B
Q34. What is a template literal in JavaScript?
A. A string inside quotes
B. A string written with backticks allowing interpolation
C. A JSON object
D. A CSS style rule
Show Answer
Answer: B
Q35. What does the this keyword usually refer to inside a method?
A. The global object only
B. The current object
C. A random value
D. The DOM tree root
Show Answer
Answer: B
Q36. What is an array in JavaScript?
A. A single number
B. A function
C. A list of ordered values
D. A Boolean value
Show Answer
Answer: C
Q37. Which method adds a new element to the end of an array?
A. push()
B. pop()
C. shift()
D. join()
Show Answer
Answer: A
Q38. Which built-in method removes the last array element?
A. delete()
B. pop()
C. remove()
D. trim()
Show Answer
Answer: B
Q39. What is the DOM in JavaScript?
A. A database
B. A programming language
C. A representation of the HTML page structure
D. A CSS rule system
Show Answer
Answer: C
Q40. Which method selects the first element that matches a CSS selector?
A. getElement()
B. select()
C. querySelector()
D. findElement()
Show Answer
Answer: C
Q41. What is an event in JavaScript?
A. A CSS change
B. A browser notification
C. A user action like click or keypress
D. A server update
Show Answer
Answer: C
Q42. Which method prevents a default browser action like form submit?
A. stop()
B. preventDefault()
C. cancel()
D. block()
Show Answer
Answer: B
Q43. What is the Fetch API used for?
A. Styling elements
B. Sending HTTP requests
C. Animating images
D. Storing cookies
Show Answer
Answer: B
Q44. What is NaN in JavaScript?
A. Null value
B. Not a Number
C. A Boolean
D. A function name
Show Answer
Answer: B
Q45. Which keyword is used to write an asynchronous function?
A. await
B. async
C. defer
D. promise
Show Answer
Answer: B
Q46. What does the JavaScript debugger statement do?
A. Deletes variables
B. Acts as a breakpoint during debugging
C. Restarts the script
D. Closes the browser tab
Show Answer
Answer: B
Q47. What is a Promise in JavaScript?
A. A loop
B. A placeholder for a future value
C. A string method
D. A DOM element type
Show Answer
Answer: B
Q48. What is the purpose of the await keyword?
A. To pause execution until a Promise is resolved
B. To declare a function
C. To create a loop
D. To define a variable
Show Answer
Answer: A
Q49. What will console.log(NaN === NaN) return?
A. true
B. false
C. undefined
D. error
Show Answer
Answer: B
Q50. What does the toString() method do?
A. Converts a string to a number
B. Converts a value to a string
C. Converts text to upper case
D. Removes spaces from text
Show Answer
Answer: B
Q51. Which array method runs a function on every element?
A. loop()
B. repeat()
C. forEach()
D. every()
Show Answer
Answer: C
Q52. What does toLocaleString() generally return?
A. A browser language code
B. A number formatted based on the user’s region
C. A CSS color name
D. A JSON object string
Show Answer
Answer: B
Q53. Which method replaces part of a string using a pattern?
A. change()
B. swap()
C. replace()
D. update()
Show Answer
Answer: C
Q54. What does the map() method return?
A. The same array modified
B. A new array with transformed values
C. A Boolean result
D. A random number
Show Answer
Answer: B
Q55. Which of the following is true about JavaScript variable names?
A. They must start with a letter or _
B. They are case-sensitive
C. Both A and B
D. None of the above
Show Answer
Answer: C
Q56. Which command prints the current page?
A. print.page()
B. browser.print()
C. window.print()
D. page.print()
Show Answer
Answer: C
Q57. What is a global variable in JavaScript?
A. A variable created inside a function
B. A variable available everywhere
C. A constant value
D. A built-in object property
Show Answer
Answer: B
Q58. Which property returns the length of a string?
A. value
B. count
C. length
D. size
Show Answer
Answer: C
Q59. What does valueOf() return when used on a Boolean?
A. A string
B. A number
C. The primitive Boolean value
D. undefined
Show Answer
Answer: C
Q60. Which method converts a string to lowercase?
A. lower()
B. toLowerCase()
C. caseLower()
D. stringLower()
Show Answer
Answer: B
Q61. What is an arrow function commonly used for?
A. Shorter function expressions
B. Loop creation
C. Styling pages
D. Storing data in localStorage
Show Answer
Answer: A
Q62. Which JavaScript array method removes and returns the last element?
A. pop()
B. remove()
C. last()
D. tail()
Show Answer
Answer: A
Q63. Which method converts an array into a string?
A. stringify()
B. toString()
C. convert()
D. cast()
Show Answer
Answer: B
Q64. Which HTML tag is used to include JavaScript code?
A. <code>
B. <js>
C. <script>
D. <run>
Show Answer
Answer: C
Q65. How do you access an element with id=”title” in JavaScript?
A. document.get(“title”)
B. document.title()
C. document.getElementById(“title”)
D. document.id(“title”)
Show Answer
Answer: C
Q66. How do you link an external JavaScript file named app.js?
A. <script file=”app.js”></script>
B. <script src=”app.js”></script>
C. <js src=”app.js”></js>
D. <script href=”app.js”></script>
Show Answer
Answer: B
Q67. What will console.log(5 + “5”) output?
A. 10
B. “10”
C. “55”
D. error
Show Answer
Answer: C
Q68. What does lastIndexOf() return when the value is not found?
A. 0
B. null
C. undefined
D. −1
Show Answer
Answer: D
Q69. Is JavaScript the same as Java?
A. Yes
B. No
C. Only in ES6
D. Only in web browsers
Show Answer
Answer: B
Q70. What will eval(“3 * 4”) return?
A. “12”
B. 12
C. 34
D. 3.4
Show Answer
Answer: B
Q71. Which method selects all matching elements in the DOM?
A. querySelector()
B. querySelectorAll()
C. getElement()
D. selectAll()
Show Answer
Answer: B
Q72. Which queue handles Promise callbacks?
A. Render queue
B. Task queue
C. Microtask queue
D. Event queue
Show Answer
Answer: C
Q73. Which HTTP header helps prevent clickjacking?
A. Cache-Control
B. Content-Type
C. X-Frame-Options
D. Access-Control-Allow-Methods
Show Answer
Answer: C
Q74. Why is eval() generally avoided?
A. It is slow
B. It can be unsafe with user input
C. It increases code size
D. All of the above
Show Answer
Answer: D
Q75. Which command is used to install a package in Node.js?
A. node install
B. install npm
C. npm install
D. npm run install
Show Answer
Answer: C
Q76. Which method reads a file asynchronously in Node.js?
A. fs.read()
B. fs.readFile()
C. fs.readFileSync()
D. fs.openFile()
Show Answer
Answer: B
Q77. Which Web API allows storing data in the browser that remains even after closing the tab?
A. sessionStorage
B. localStorage
C. cacheStorage
D. clipboard API
Show Answer
Answer: B
Q78. Which DOM property returns the parent element of a node?
A. parentElement
B. rootNode
C. ownerNode
D. baseNode
Show Answer
Answer: A
Q79. Which Promise method resolves as soon as any promise is settled?
A. Promise.all()
B. Promise.allSettled()
C. Promise.race()
D. Promise.resolve()
Show Answer
Answer: C
Q80. What type of scope is created when using let inside a block?
A. Function scope
B. Global scope
C. Class scope
D. Block scope
Show Answer
Answer: D
Q81. Which built-in function returns the smallest value?
A. Math.smallest()
B. Math.min()
C. Math.low()
D. Math.floor()
Show Answer
Answer: B
Q82. Which event fires when a user clicks an element?
A. onchange
B. onhover
C. onclick
D. onpress
Show Answer
Answer: C
Q83. What is the difference between JavaScript and Java?
A. They are the same
B. JavaScript is mainly browser-based scripting
C. JavaScript is compiled
D. JavaScript is a database language
Show Answer
Answer: B
Q84. Which method rounds a number to the nearest integer?
A. Math.floor()
B. Math.ceil()
C. Math.round()
D. Math.fix()
Show Answer
Answer: C
Q85. Which of the following correctly creates an array?
A. var list = {1,2,3}
B. var list = [1,2,3]
C. var list = (1,2,3)
D. var list = “1,2,3”
Show Answer
Answer: B
Q86. Which syntax correctly starts a for loop?
A. for (i < 5; i++)
B. for i = 1 to 5
C. for (i = 0; i < 5; i++)
D. loop(i < 5)
Show Answer
Answer: C
Q87. Which syntax correctly starts a while loop?
A. while i < 10
B. while (i < 10)
C. loop while (i < 10)
D. repeat (i < 10)
Show Answer
Answer: B
Q88. Which operator checks if two values are not equal?
A. !=
B. <>
C. !===
D. not=
Show Answer
Answer: A
Q89. Which operator checks strict equality?
A. =
B. ==
C. ===
D. eq
Show Answer
Answer: C
Q90. How do you call a JavaScript function named runTest?
A. function runTest
B. call runTest
C. exec runTest()
D. runTest()
Show Answer
Answer: D
Q91. Which syntax correctly defines a function?
A. define run(){}
B. function run(){}
C. create run(){}
D. make run(){}
Show Answer
Answer: B
Q92. Which syntax correctly writes a multi-line comment?
A. # comment
B. // comment
C. <!– comment –>
D. /* comment */
Show Answer
Answer: D
Q93. Which syntax correctly writes a single-line comment?
A. # comment
B. // comment
C. /* comment */
D. — comment
Show Answer
Answer: B
Q94. Is JavaScript case-sensitive?
A. Yes
B. No
C. Only variable names
D. Only functions
Show Answer
Answer: A
Q95. Where can JavaScript code be placed in an HTML page?
A. Only in the head
B. Only in the body
C. Either head or body
D. Only in external files
Show Answer
Answer: C
Q96. What is the type of null in JavaScript?
A. null
B. object
C. undefined
D. number
Show Answer
Answer: B
Q97. Which keyword declares a variable with block scope?
A. global
B. var
C. let
D. scope
Show Answer
Answer: C
Q98. Which operator checks equality without converting types?
A. ==
B. ===
C. !=
D. =
Show Answer
Answer: B
Q99. What does NaN stand for in JavaScript?
A. Not a Number
B. New and Null
C. None Available Now
D. Numeric and Null
Show Answer
Answer: A
Q100. What feature allows using “await” outside of functions in modern JavaScript modules?
A. Async IIFE
B. Top-level await
C. Global await mode
D. Module async mode
Show Answer
Answer: B
Conclusion
Practising JavaScript MCQ and quiz questions is one of the best ways to revise concepts and get ready for interviews or coding rounds. Keep learning and exploring new questions to build confidence. You can also go through these Top 50 JavaScript Interview Questions and Answers for deeper interview preparation.
Resources and References:
- Learn JavaScript on MDN Web Docs
https://developer.mozilla.org/en-US/docs/Web/JavaScript - Read the ECMAScript Official Language Specification
https://tc39.es/ecma262/
