JavaScript Quiz- Web Developers

Are you involved in creating large websites and using HTML5, CSS, and JS? Then take some time and spare 5 minutes to attempt this JavaScript quiz. It includes 25 questions that would test your end-to-end knowledge of JavaScript.

JavaScript is the most famous, dynamic, and untyped client-side scripting language. While coding, you don’t have to declare the type for variables and methods. It supports object-oriented and functional programming models and has built-in support for strings, arrays, dates, and regular expressions.

Checkout: 20 JavaScript Coding Tips

With the help of JS and CSS, you can create responsive designs that improve the user experience and add dynamic behavior like displaying pages without waiting for the server.

In addition to the skills mentioned, building a remarkable web page also requires the knowledge of HTML5. So you may not want to miss out on our latest HTML CSS quiz.

This quiz covers many JavaScript questions that will help a web developer check his knowledge of the language features. The rest of the quiz contains coding snippets to evaluate your programming ability.

JavaScript Quiz – 25 Questions

", options: [ "

", "

null

", "

undefined

" ], answer: 0 }, { question: "2. What does this code output?

function test() {
 if(true) { var a = 5; }
 alert(a);
}

", options: [ "

", "

null

", "

undefined

" ], answer: 1 }, { question: "3. What will be alerted?

var a = 5;
function update() { a = 6; }
function show() { alert(a); }

", options: [ "

", "

null

", "

undefined

", "

" ], answer: 4 }, { question: "4. What does this output?

function setGlobal() { window.a = 3; }
function show() { alert(a); }

", options: [ "

", "

null

", "

undefined

" ], answer: 1 }, { question: "5. What is the output?

var x = [typeof x, typeof y][1];
typeof typeof x;

", options: [ "

'number'

", "

'string'

", "

'undefined'

", "

'object'

" ], answer: 1 }, { question: "6. What are the alert values?

var a = 6;
function test() { var a = 7; function inner() { var a = 8; alert(a); } inner(); alert(a); }
test(); alert(a);

", options: [ "

6; 7; 8

", "

7; 6; 8

", "

8; 7; 6

", "

8; 6; 7

" ], answer: 2 }, { question: "7. What is the output?

function getFunc() { var a = 7; return function(b) { alert(a+b); } }
var f = getFunc(); f(5);

", options: [ "

", "

null

", "

undefined

", "

" ], answer: 4 }, { question: "8. What does `typeof` return?", options: [ "Unary type operator", "Returns a string", "Both", "None" ], answer: 2 }, { question: "9. Can functions take anonymous functions?", options: [ "True", "False" ], answer: 0 }, { question: "10. What is a callback function?", options: [ "Function passed as argument", "Triggered event reaction", "Both", "None" ], answer: 2 }, { question: "11. How to create an object?", options: [ "

var obj = Object();

", "

var obj = new Object();

", "

var obj = new OBJECT();

", "

var obj = new obj();

" ], answer: 1 }, { question: "12. Boolean method returning string?", options: [ "

toSource()

", "

valueOf()

", "

toString()

", "

None

" ], answer: 2 }, { question: "13. Function replacing substrings?", options: [ "

concat()

", "

match()

", "

replace()

", "

search()

" ], answer: 2 }, { question: "14. Function making text big?", options: [ "

anchor()

", "

big()

", "

blink()

", "

italics()

" ], answer: 1 }, { question: "15. Array method returning new array?", options: [ "

concat()

", "

pop()

", "

push()

", "

some()

" ], answer: 0 }, { question: "16. Array method iterating elements?", options: [ "

concat()

", "

every()

", "

filter()

", "

forEach()

" ], answer: 3 }, { question: "17. Method modifying array elements?", options: [ "

toSource()

", "

sort()

", "

splice()

", "

unshift()

" ], answer: 2 }, { question: "18. Which statements are correct?", options: [ "JS is lightweight", "JS is network-centric", "JS integrates with Java", "All" ], answer: 3 }, { question: "19. How to check argument types?", options: [ "Using typeof", "Using getType", "Both", "None" ], answer: 0 }, { question: "20. Method removing last array item?", options: [ "

last()

", "

get()

", "

pop()

", "

None

" ], answer: 2 }, { question: "21. Method displaying exponential format?", options: [ "

toExponential()

", "

toFixed()

", "

toPrecision()

", "

toLocaleString()

" ], answer: 0 }, { question: "22. Method formatting number locale-wise?", options: [ "

toExponential()

", "

toFixed()

", "

toLocaleString()

", "

toString()

" ], answer: 2 }, { question: "23. Function matching regex?", options: [ "

concat()

", "

match()

", "

search()

", "

replace()

" ], answer: 1 }, { question: "24. Function uppercasing text locale-wise?", options: [ "

toLocaleUpperCase()

", "

toUpperCase()

", "

toString()

", "

substring()

" ], answer: 0 }, { question: "25. Method creating hypertext link?", options: [ "

link()

", "

sub()

", "

sup()

", "

small()

" ], answer: 0 } ];

Answer Key with Reasoning

Here’s a concise reasoning table explaining the correct answers for all 25 JavaScript questions:

Q#	Correct Answer	Reasoning
1	`7`	The value of `a` is updated to `7` inside the `if` block.
2	`5`	`var` variables are function-scoped, so `a` is accessible inside `alert()`.
3	`6`	The function `update()` changes the global variable `a` to `6`.
4	`3`	`window.a = 3` makes `a` a global variable accessible in `second()`.
5	`'string'`	`typeof x` returns a string, and `typeof typeof x` results in `"string"`.
6	`8; 7; 6`	`8` (inner function), `7` (middle scope), `6` (global).
7	`12`	`getFunc()` returns a function that adds `7 + 5`.
8	`Both`	`typeof` is a unary operator that returns a string representation of a variable’s type.
9	`True`	JavaScript allows passing anonymous functions as arguments.
10	`Both`	A callback is a function passed as an argument to another function.
11	`var obj = new Object();`	This is the correct way to create an object using the `Object` constructor.
12	`toString()`	Converts Boolean values (`true/false`) to string format.
13	`replace()`	This method replaces specified substrings in a string.
14	`big()`	This method makes text larger in HTML.
15	`concat()`	Returns a new array by merging two or more arrays.
16	`forEach()`	Iterates over an array and executes a function for each element.
17	`splice()`	Modifies the array by adding/removing elements.
18	`All`	JavaScript is lightweight, network-centric, and integrates with Java.
19	`Using typeof`	`typeof` checks the type of a variable or value.
20	`pop()`	Removes and returns the last element of an array.
21	`toExponential()`	Converts numbers to exponential notation.
22	`toLocaleString()`	Formats numbers based on the locale settings.
23	`match()`	Matches a string against a regular expression and returns results.
24	`toLocaleUpperCase()`	Converts text to uppercase while respecting locale settings.
25	`link()`	Creates a hyperlink using the `link()` method.

Key Takeaways from JavaScript Quiz

So, did you enjoy the quiz? We hope you liked the different questions related to the JavaScript concept. We want to thank you for taking the time to try this quiz.

However, if you are a programming geek, you can brainstorm further with more cool quizzes on web development and read related programming articles from our blog. Now, click to start the JavaScript quiz.

Also Read: Latest JavaScript Interview Questions and Answers

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TechBeamers