JavaScript is one of the flexible and popular languages for developing applications in the world. Whether it is presentation layer or server-side script development, it has become one of the basic languages to learn for developers-teachers. Coding challenges are perfect to learn JavaScript and advance your coding skills to the next level. Regardless if one is a beginner or looking for a promotion, these challenges will enhance working on the problem-solving element and enhance confidence in constructing optimal codes.
On this blog, the following features the Top 05 JavaScript Coding Challenges for transforming students into JavaScript gurus: On the way, it is necessary to learn how these challenges help in the development of skills, why they are critical, and how you can use them to reach the job level.
The FizzBuzz problem is one of the most basic yet common coding problem that is often used to possibly evaluate a developer’s implementation of basic logic and control structures. It involves printing numbers in a specified range (usually 1 to 100) with special rules:
Here the focus is to use a loop to go through numbers from one up to one hundred and such conditions will have to be met before what is to be printed is determined. Let’s break down the task:
Here is the step-by-step logic to solve the problem:
Here is a simple implementation of the FizzBuzz challenge using JavaScript:
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for (let i = 1; i <= 100; i++) {
if (i % 3 === 0 && i % 5 === 0) {
console.log("FizzBuzz");
} else if (i % 3 === 0) {
console.log("Fizz");
} else if (i % 5 === 0) {
console.log("Buzz");
} else {
console.log(i);
}
}
Loops:
Conditional Statements:
Modular Arithmetic:
Wrong Order of Conditions: When found i % 3 === 0 or i % 5 === 0 before verifying the condition i % 3 === 0 && i % 5 === 0, it will give false results. As a rule check for “FizzBuzz” first.
Using the Assignment Operator = instead of == or ===: This leads to logical fallacies and flawed thinking which results in an element of randomness or unpredictability.
Off-by-One Errors: Take care so as not to abuse the range set within the loop (the range from 1 to 100 in this exercise).
Palindrome refers to a word which is read in the same way right through from left to right and also from right to left, same applies to a phrase, number or sequence of anything. For instance, the word ‘‘madam ‘‘ or the number 121 are palindromes in this sense since they read the same when spelled or spoken backwards.
This challenge we should come up with a JavaScript function that determines if an a given input, which could be a string or a number, is a palindrome. This exercise is also useful in the practical aspects of the programming basics including strings, conditional statements, loops and recursion.
The task is simple: To solve this problem one need to determine if an input value (a string of characters, a number) remains the same if traced forward and backward. Let’s break down the process:
Here’s the step-by-step approach to solving the palindrome checker challenge:
Normalize the input:
Reverse the input:
Here’s an implementation of a basic palindrome checker using JavaScript:
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function isPalindrome(input) {
// Convert the input to a string and normalize it
let str = input.toString().toLowerCase().replace(/[^a-z0-9]/g, '');
// Reverse the string
let reversedStr = str.split('').reverse().join('');
// Compare the original and reversed strings
return str === reversedStr;
}
// Test cases
console.log(isPalindrome("madam")); // true
console.log(isPalindrome("hello")); // false
console.log(isPalindrome("A man, a plan, a canal, Panama")); // true
console.log(isPalindrome(121)); // true
console.log(isPalindrome(123)); // false
split(), reverse(), and join(): These are important functions in JavaScript that is used to split a string into an array reverses the array and then joins it back to a string.
Specifically, the input string is sanitized so that we remove any unwanted character from the string using the regular expression of /[^a-z0-9]/g.
Loops: In other examples, you can omit the reverse() function and instead you’ll have to loop through the string and check if the first character is similar to the last, gradually moving inwards.
Here’s an alternative implementation using a loop:
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function isPalindromeLoop(input) {
let str = input.toString().toLowerCase().replace(/[^a-z0-9]/g, '');
let len = str.length;
for (let i = 0; i < len / 2; i++) {
if (str[i] !== str[len - 1 - i]) {
return false;
}
}
return true;
}
Here’s a recursive solution:
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function isPalindromeRecursive(input) {
let str = input.toString().toLowerCase().replace(/[^a-z0-9]/g, '');
// Base case: a string of length 0 or 1 is a palindrome
if (str.length <= 1) return true;
// Check the first and last characters
if (str[0] === str[str.length - 1]) {
return isPalindromeRecursive(str.slice(1, str.length - 1));
} else {
return false;
}
}
In all approaches, if statements are used to decide whether the string or number is a palindrome by comparing characters in the original and reversed versions.
Using String vs Number: One might experience type-related issues if he or she forgets to convert a number into a string.
Sorting is a basic category in computation and computing or in general information technology. Arranging entails ensuring that the elements of an established array are aligned according to a proper sequence which could be ascending or descending order. Though, one can use a predefined method of java script called sort () to get the arrays sorted, using sorting algorithms like Bubble Sort, Quick Sort, Merge Sort also exhaustive in bigger data sets will help in understanding how the sorting works.
In this challenge students will practice writing their own sorting functions implementing some of the most commonly used sorting algorithms, examine their performance, and learn how they are constructed.
Here there are some of them; they differ in terms of complexity and the amount of time they take to sort the items. Three common ones are:
Bubble Sort: An algorism that just goes through the list cyclically and, if two items are in the wrong order, swaps them.
Quick Sort: An algorithm which repeatedly divides the given array into two parts, and then separately sorts each half with help of this algorithm.
Merge Sort: A further example of a divide-and-conquer algorithm which partitions the array, sorts the partitions by using the same algorithm, then merging the sorted partitions.
Algorithm Overview
Bubble Sort is probably the simplest sorting algorithm out there. It always goes through two items and if the items are out of order then they are swapped. This goes on until the whole array of elements is sorted.
Step-by-Step Logic
Code Implementation in JavaScript
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function bubbleSort(arr) {
let n = arr.length;
let swapped;
// Outer loop for each pass
for (let i = 0; i < n; i++) {
swapped = false;
// Inner loop for comparison of adjacent elements
for (let j = 0; j < n - i - 1; j++) {
if (arr[j] > arr[j + 1]) {
// Swap elements if they are in the wrong order
let temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
swapped = true;
}
}
// If no two elements were swapped, array is already sorted
if (!swapped) break;
}
return arr;
}
// Test case
console.log(bubbleSort([64, 34, 25, 12, 22, 11, 90])); // Output: [11, 12, 22, 25, 34, 64, 90]
Time Complexity
Pros and Cons
Algorithm Overview
Quick Sort is a highly efficient, divide-and-conquer algorithm. It works by selecting a pivot element from the array and partitioning the other elements into two sub-arrays: those less than the pivot and those greater than or equal to the pivot. These sub-arrays are then recursively sorted.
Step-by-Step Logic
Code Implementation in JavaScript
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function quickSort(arr) {
if (arr.length <= 1) return arr;
let pivot = arr[arr.length - 1]; // Choosing the last element as the pivot
let left = [];
let right = [];
for (let i = 0; i < arr.length - 1; i++) {
if (arr[i] < pivot) {
left.push(arr[i]);
} else {
right.push(arr[i]);
}
}
// Recursively sort the left and right arrays, and concatenate them with the pivot
return [...quickSort(left), pivot, ...quickSort(right)];
}
// Test case
console.log(quickSort([64, 34, 25, 12, 22, 11, 90])); // Output: [11, 12, 22, 25, 34, 64, 90]
Time Complexity
Pros and Cons
Algorithm Overview
Merge Sort is another divide-and-conquer algorithm that recursively splits the array into halves, sorts each half, and then merges the sorted halves back together. It ensures that the array is split into smaller arrays that are easier to sort.
Step-by-Step Logic
Code Implementation in JavaScript
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function mergeSort(arr) {
if (arr.length <= 1) return arr;
// Find the middle of the array
const middle = Math.floor(arr.length / 2);
const left = arr.slice(0, middle);
const right = arr.slice(middle);
// Recursively sort both halves and merge them
return merge(mergeSort(left), mergeSort(right));
}
// Helper function to merge two sorted arrays
function merge(left, right) {
let result = [];
let i = 0;
let j = 0;
while (i < left.length && j < right.length) {
if (left[i] < right[j]) {
result.push(left[i]);
i++;
} else {
result.push(right[j]);
j++;
}
}
// Concatenate any remaining elements
return result.concat(left.slice(i)).concat(right.slice(j));
}
// Test case
console.log(mergeSort([64, 34, 25, 12, 22, 11, 90])); // Output: [11, 12, 22, 25, 34, 64, 90]
Time Complexity
Pros and Cons
1. Overview of the Task: Finding the Longest Word
Among the basic problems to which developers can solve coding problems, one that often arises is to create an algorithm to search for the longest word in a string. The task is to create an algorithm in the form of JAVASCRIPT that should input a sentence (or string) and output the longest word in that string.In this task, the input string must be divided into an array of words for which the next step is to loop in the array to keep track of the longest word.
The challenge is simple: in view of this means that for any given string (sentence), it will be necessary to establish which word in the string is longer than the other by computing and comparing the number of characters in the string that correspond to a particular word.
For example:
Input: “That’s a really dumb phrase”
Output: is that one word in the sentence that spell has looked for but you jumped and you run away from it? (as you can notice the word ‘jumped’ has got the highest number of characters, that is 6).
The algorithm for solving this problem can be broken down into these steps:
Here is an implementation of the function to find the longest word in a string:
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function findLongestWord(str) {
// Step 1: Split the string into an array of words
let words = str.split(' ');
// Step 2: Initialize a variable to store the longest word
let longestWord = "";
// Step 3: Loop through the array of words
for (let i = 0; i < words.length; i++) {
// Step 4: Check if the current word is longer than the longest word so far
if (words[i].length > longestWord.length) {
longestWord = words[i]; // Update the longest word
}
}
// Step 5: Return the longest word
return longestWord;
}
// Test case
console.log(findLongestWord("The quick brown fox jumped over the lazy dog")); // Output: "jumped"
We can also solve this problem using JavaScript’s reduce() method, which is a powerful function for reducing an array to a single value based on a given logic.
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function findLongestWord(str) {
return str.split(' ').reduce(function(longest, currentWord) {
return currentWord.length > longest.length ? currentWord : longest;
}, "");
}
// Test case
console.log(findLongestWord("The quick brown fox jumped over the lazy dog")); // Output: "jumped"
The split() function is crucial as it allows for the transformation of the string into an array. Depending on the problem you solve, you can divide by spaces ‘ ’ or any other symbol such as ‘,’, ‘.’, etc.
In the other approach, we utilized reduce() which is useful in processing of the array in functional programming paradigm. It compares each word and cuts down the given array to its longest word.
The classic approach employs the use of for loop to go through all the words in the array of words.
Algebraically within this loop, there is an if-statement that will check whether the current
word is longer than the longest word, ever found.
Among the most straightforward operations that can be performed on linear arrays, one can mention the task of summing up all the elements. In this challenge, you are required to merge a function that takes in an array and SUM all the input numbers located in the Array. This exercise may look easy, but it is very important in mastering how arrays and their methods work in JavaScript.
Calculating the sum of array elements is useful in order to gain experience in using array handling functions, such as reduce(), which is one of the most effective tools for array manipulation. The reduce() method gives a functional form to work than usual loops, which is more accurate for such scenarios.
The task is to find the sum of any given elements of the array. For example:
Input: [1, 2, 3, 4, 5]
Output: 15 (because 1+2+3+4+5=15)
It is useful for perceiving how the arrays work in JavaScript and for the acquaintance with such methods as reduce(). The objective is to get an understanding of how looping mechanisms work, how to work with higher functions, and working with collections in data.
There are two main approaches to solve this problem:
Approach 1: Using a for Loop
Code Implementation
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function sumArray(arr) {
let sum = 0; // Step 1: Initialize the sum
for (let i = 0; i < arr.length; i++) { // Step 2: Iterate through the array
sum += arr[i]; // Step 3: Add each element to the sum
}
return sum; // Step 4: Return the total sum
}
// Test case
console.log(sumArray([1, 2, 3, 4, 5])); // Output: 15
Approach 2: Using reduce()
Code Implementation with reduce()
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function sumArray(arr) {
return arr.reduce((accumulator, currentValue) => accumulator + currentValue, 0);
}
// Test case
console.log(sumArray([1, 2, 3, 4, 5])); // Output: 15
How reduce() Works:
On each pass through the array, reduce() adds the currentValue to the accumulator and updates the accumulator. Once all elements have been processed, the final value of the accumulator is returned as the sum.
Empty Arrays: The reduce() method handles empty arrays gracefully when the initial value of the accumulator is provided. For an empty array, the sum would be 0.
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console.log(sumArray([])); // Output: 0
Negative Numbers: If the array contains negative numbers, the function will correctly sum them.
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console.log(sumArray([1, -2, 3, -4, 5])); // Output: 3
Non-Numeric Values: If non-numeric values are present in the array, they will need to be filtered out before summing to avoid unexpected behavior.
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function sumArray(arr) {
return arr.filter(item => typeof item === 'number')
.reduce((accumulator, currentValue) => accumulator + currentValue, 0);
}
console.log(sumArray([1, '2', 3, true, 5])); // Output: 9 (non-numeric values are ignored)
Both types of solutions based on a loop or reduce() work well with an O(n) time complexity: the program’s speed increases linearly with the size of the array. Yet again, reduce() is cleaner and more concise in functional programing paradigms, making it preferable in Modern JavaScript code.
Sum Only Positive Elements: Modify the function to only sum positive numbers in the array.
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function sumPositiveNumbers(arr) {
return arr.filter(num => num > 0).reduce((acc, num) => acc + num, 0);
}
console.log(sumPositiveNumbers([1, -2, 3, -4, 5])); // Output: 9
Sum of Squared Elements: Calculate the sum of the squares of all elements in the array.
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function sumOfSquares(arr) {
return arr.reduce((acc, num) => acc + num * num, 0);
}
console.log(sumOfSquares([1, 2, 3])); // Output: 14 (1² + 2² + 3² = 14)
Sum Using Recursion: Implement a recursive solution for summing array elements (without using loops or reduce()).
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function sumArrayRecursive(arr) {
if (arr.length === 0) return 0;
return arr[0] + sumArrayRecursive(arr.slice(1));
}
console.log(sumArrayRecursive([1, 2, 3, 4, 5])); // Output: 15
Challenge |
Key Concepts |
Methods/Functions |
Why It’s Important |
Example Input |
Example Output |
1. FizzBuzz Challenge |
Loops (for/while), Conditionals (if-else), Modular arithmetic (%) |
if, %, console.log() |
Demonstrates ability to use loops, conditionals, and modulus operator. |
1 to 100 |
FizzBuzz for multiples of 3 and 5 |
2. Palindrome Checker |
Fragment manipulation (split(), reverse(), join()), Loops, Conditional logic |
split(), reverse(), join(), if |
Practices string manipulation and helps understand reversing strings and conditional checks. |
"racecar" |
true |
3. Array Sorting |
Sorting algorithms (Bubble sort, Quick sort, Merge sort), Nested loops |
Custom sorting algorithms, sort() |
Teaches the inner workings of sorting algorithms, providing insight into how sorting works for larger arrays. |
[5, 2, 9, 1] |
[1, 2, 5, 9] |
4. Find the Longest Word in a String |
Data type conversion (split()), Array functions (length), Loops, Conditional checks |
split(), length, for loop, reduce() |
Familiarizes with string & array functions, useful in front-end development and text processing. |
"The quick brown fox" |
"quick" |
5. Sum of Array Elements |
Arrays, Array methods (reduce()), Loop control, Higher-order functions |
reduce(), for loop |
Introduces handling collections of data, reduce() method, and looping, essential for data manipulation. |
[1, 2, 3, 4, 5] |
15 |
By overcoming these codings, students will gain the knowledge and skills needed to perform in JavaScript. This is why irrespective of whether you want to become a front-end developer, full-stack developer or a software engineer, solving real coding problems is of paramount importance. Many of the best IT training centers in Dubai conduct JavaScript classes keeping in mind real-life coding problems like these.
The right training program for JavaScript lets you extend your knowledge and skills, refine your practical coding abilities, as well as improve your skills in coding interviews. If you want to do the search for a JavaScript course in Dubai, make sure that you should go for that course which also contains theoretical as well as practical exercises to prepare yourself for coding.
That is why the Top 9 JavaScript Coding Challenges described in this blog provide a step-by-step introduction from plain problem-solving to algorithmic problem-solving. For the most part, these challenges are not mere guess works; they are commonly applied in employment interviews and assist students in gaining confidence when coding.
Regardless of whether you are participating in JavaScript classes, or you are studying on your own, these challenges will enhance your abilities significantly. For even better results, consider joining one of the best IT training centers that offer JavaScript course in Dubai but ensure that they provide an opportunity to practice the code. By continuously going through this process, you stand a good chance of becoming a JavaScript coder guru.
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