w3resource logo

:

JavaScript Exercises

JavaScript functions - Exercises, Practice, Solution

JavaScript functions [29 exercises with solution]

[An editor is available at the bottom of the page to write and execute the scripts.]

1. Write a JavaScript function that reverse a number. Go to the editor
Example x = 32243;
Expected Output : 34223
Click me to see the solution

2. Write a JavaScript function that checks whether a passed string is palindrome or not? Go to the editor
A palindrome is word, phrase, or sequence that reads the same backward as forward, e.g., madam or nurses run.
Click me to see the solution

3. Write a JavaScript function that generates all combinations of a string. Go to the editor
Example string : 'dog'
Expected Output : d,do,dog,o,og,g
Click me to see the solution

4. Write a JavaScript function that returns a passed string with letters in alphabetical order. Go to the editor
Example string : 'webmaster'
Expected Output : 'abeemrstw'
Assume punctuation and numbers symbols are not included in the passed string.
Click me to see the solution

5. Write a JavaScript function that accepts a string as a parameter and converts the first letter of each word of the string in upper case. Go to the editor
Example string : 'the quick brown fox'
Expected Output : 'The Quick Brown Fox '
Click me to see the solution

6. Write a JavaScript function that accepts a string as a parameter and find the longest word within the string. Go to the editor
Example string : 'Web Development Tutorial'
Expected Output : 'Development'
Click me to see the solution

7. Write a JavaScript function that accepts a string as a parameter and counts the number of vowels within the string. Go to the editor
Note : As the letter 'y' can be regarded as both a vowel and a consonant, we do not count 'y' as vowel here.
Example string : 'The quick brown fox'
Expected Output : 5
Click me to see the solution

8. Write a JavaScript function that accepts a number as a parameter and check the number is prime or not. Go to the editor
Note : A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.
Click me to see the solution

9. Write a JavaScript function which accepts an argument and returns the type. Go to the editor
Note : There are six possible values that typeof returns: object, boolean, function, number, string, and undefined.
Click me to see the solution

10. Write a JavaScript function which returns the n rows by n columns identity matrix. Go to the editor
Click me to see the solution

11. Write a JavaScript function which will take an array of numbers stored and find the second lowest and second greatest numbers, respectively. Go to the editor
Sample array : [1,2,3,4,5]
Expected Output : 2,4
Click me to see the solution.

12. Write a JavaScript function which says whether a number is perfect. Go to the editor
According to Wikipedia : In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect number is a number that is half the sum of all of its positive divisors (including itself).
Example : The first perfect number is 6, because 1, 2, and 3 are its proper positive divisors, and 1 + 2 + 3 = 6. Equivalently, the number 6 is equal to half the sum of all its positive divisors: ( 1 + 2 + 3 + 6 ) / 2 = 6. The next perfect number is 28 = 1 + 2 + 4 + 7 + 14. This is followed by the perfect numbers 496 and 8128.
Click me to see the solution.

13. Write a JavaScript function to compute the factors of a positive integer. Go to the editor
Click me to see the solution.

14. Write a JavaScript function to convert an amount to coins. Go to the editor
Sample function : amountTocoins(46, [25, 10, 5, 2, 1])
Here 46 is the amount. and 25, 10, 5, 2, 1 are coins.
Output : 25, 10, 10, 1
Click me to see the solution.

15. Write a JavaScript function to compute the value of bn where n is the exponent and b is the bases. Accept b and n from the user and display the result. Go to the editor
Click me to see the solution.

16. Write a JavaScript function to extract unique characters from a string. Go to the editor
Example string : "thequickbrownfoxjumpsoverthelazydog"
Expected Output : "thequickbrownfxjmpsvlazydg"
Click me to see the solution.

17. Write a JavaScript function to  get the number of occurrences of each letter in specified string. Go to the editor
Click me to see the solution.

18. Write a function for searching JavaScript arrays with a binary search. Go to the editor
Note : A binary search searches by splitting an array into smaller and smaller chunks until it finds the desired value.
Click me to see the solution.

19. Write a JavaScript function that returns array elements larger than a number. Go to the editor
Click me to see the solution.

20. Write a JavaScript function that generates a string id (specified length) of random characters. Go to the editor
Sample character list : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Click me to see the solution.

21. Write a JavaScript function to get all possible subset with a fixed length (for example 2) combinations in an array. Go to the editor
Sample array : [1, 2, 3] and subset length is 2
Expected output : [[2, 1], [3, 1], [3, 2], [3, 2, 1]]
Click me to see the solution.

22. Write a JavaScript function that accepts two arguments, a string and a letter and the function will count the number of occurrences of the specified letter within the string. Go to the editor
Sample arguments : 'w3resource.com', 'o'
Expected output : 2
Click me to see the solution

23. Write a JavaScript function to find the first not repeated character. Go to the editor
Sample arguments : 'abacddbec'
Expected output : 'e'
Click me to see the solution

24. Write a JavaScript function to apply Bubble Sort algorithm. Go to the editor
Note : According to wikipedia "Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that works by repeatedly stepping through the list to be sorted, comparing each pair of adjacent items and swapping them if they are in the wrong order".
Sample array : [12, 345, 4, 546, 122, 84, 98, 64, 9, 1, 3223, 455, 23, 234, 213]
Expected output : [3223, 546, 455, 345, 234, 213, 122, 98, 84, 64, 23, 12, 9, 4, 1]
Click me to see the solution

25. Write a JavaScript function that accept a list of country names as input and returns the longest country name as output. Go to the editor
Sample function : Longest_Country_Name(["Australia", "Germany", "United States of America"])
Expected output : "United States of America"
Click me to see the solution

26. Write a JavaScript function to find longest substring in a given a string without repeating characters. Go to the editor
Click me to see the solution

27. Write a JavaScript function that returns the longest palindrome in a given string. Go to the editor

Note: According to Wikipedia "In computer science, the longest palindromic substring or longest symmetric factor problem is the problem of finding a maximum-length contiguous substring of a given string that is also a palindrome. For example, the longest palindromic substring of "bananas" is "anana". The longest palindromic substring is not guaranteed to be unique; for example, in the string "abracadabra", there is no palindromic substring with length greater than three, but there are two palindromic substrings with length three, namely, "aca" and "ada".
In some applications it may be necessary to return all maximal palindromic substrings (that is, all substrings that are themselves palindromes and cannot be extended to larger palindromic substrings) rather than returning only one substring or returning the maximum length of a palindromic substring.
Click me to see the solution

28. Write a JavaScript program to pass a 'JavaScript function' as parameter. Go to the editor
Click me to see the solution

29. Write a JavaScript function to get the function name. Go to the editor
Click me to see the solution

More to Come !

* To run the code mouse over on Result panel and click on 'RERUN' button.*

See the Pen JavaScript - function-exercises by w3resource (@w3resource) on CodePen.


Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.