JavaScript Problem-Solving Questions
Problem-solving is a critical skill for JavaScript developers. Whether you're preparing for interviews, coding assessments, or real-world projects, tackling JavaScript problems enhances your understanding of the language and your ability to implement effective solutions. This article provides a comprehensive guide to common problem-solving questions in JavaScript, categorized by difficulty level and type.
01. Why Focus on JavaScript Problem-Solving?
JavaScript is a versatile language used for client-side and server-side development. Problem-solving questions are designed to test:
- Understanding: How well you know JavaScript concepts.
- Efficiency: Your ability to write optimized code.
- Creativity: Your approach to solving unique challenges.
02. Beginner-Level Questions
These questions test fundamental JavaScript knowledge.
1. Reverse a String
Problem: Write a function that reverses a string.
// Solution
function reverseString(str) {
return str.split('').reverse().join('');
}
console.log(reverseString("hello")); // Output: "olleh"
2. Check for Palindromes
Problem: Determine if a string is a palindrome.
// Solution
function isPalindrome(str) {
const reversed = str.split('').reverse().join('');
return str === reversed;
}
console.log(isPalindrome("racecar")); // Output: true
console.log(isPalindrome("hello")); // Output: false
3. Sum of Array Elements
Problem: Calculate the sum of all elements in an array.
// Solution
function sumArray(arr) {
return arr.reduce((sum, num) => sum + num, 0);
}
console.log(sumArray([1, 2, 3, 4])); // Output: 10
03. Intermediate-Level Questions
These questions test your ability to apply JavaScript concepts to solve more complex problems.
1. Find the Most Frequent Element
Problem: Identify the most frequent element in an array.
// Solution
function mostFrequent(arr) {
const frequency = {};
arr.forEach(num => frequency[num] = (frequency[num] || 0) + 1);
let maxCount = 0, mostFrequent;
for (let key in frequency) {
if (frequency[key] > maxCount) {
maxCount = frequency[key];
mostFrequent = key;
}
}
return mostFrequent;
}
console.log(mostFrequent([1, 3, 2, 3, 2, 3])); // Output: 3
2. Find Prime Numbers in a Range
Problem: Write a function to find all prime numbers in a range.
// Solution
function findPrimes(start, end) {
const primes = [];
for (let i = start; i <= end; i++) {
if (isPrime(i)) primes.push(i);
}
return primes;
}
function isPrime(num) {
if (num < 2) return false;
for (let i = 2; i <= Math.sqrt(num); i++) {
if (num % i === 0) return false;
}
return true;
}
console.log(findPrimes(10, 20)); // Output: [11, 13, 17, 19]
04. Advanced-Level Questions
These questions challenge your problem-solving and algorithmic thinking.
1. Find the Longest Substring Without Repeating Characters
Problem: Write a function to find the length of the longest substring without repeating characters.
// Solution
function longestUniqueSubstring(str) {
let maxLength = 0;
let charSet = new Set();
let left = 0;
for (let right = 0; right < str.length; right++) {
while (charSet.has(str[right])) {
charSet.delete(str[left]);
left++;
}
charSet.add(str[right]);
maxLength = Math.max(maxLength, right - left + 1);
}
return maxLength;
}
console.log(longestUniqueSubstring("abcabcbb")); // Output: 3
2. Merge Overlapping Intervals
Problem: Merge overlapping intervals in an array.
// Solution
function mergeIntervals(intervals) {
intervals.sort((a, b) => a[0] - b[0]);
const result = [intervals[0]];
for (let i = 1; i < intervals.length; i++) {
const last = result[result.length - 1];
if (intervals[i][0] <= last[1]) {
last[1] = Math.max(last[1], intervals[i][1]);
} else {
result.push(intervals[i]);
}
}
return result;
}
console.log(mergeIntervals([[1, 3], [2, 6], [8, 10], [15, 18]]));
// Output: [[1, 6], [8, 10], [15, 18]]
05. Tips for Solving JavaScript Problems
Effective problem-solving involves understanding the problem and applying the right techniques:
- Understand the Problem: Break it into smaller parts and ask clarifying questions if necessary.
- Write Pseudocode: Plan your solution before writing actual code.
- Optimize: Focus on time and space complexity, especially for larger datasets.
- Test Your Code: Use different test cases to validate your solution.
06. Resources for Practice
Conclusion
Practicing JavaScript problem-solving questions prepares you for technical interviews and enhances your coding skills. Start with fundamental problems, progress to intermediate and advanced levels, and consistently apply problem-solving strategies. Utilize the provided resources to practice and refine your skills.
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