▶JavaScript Playground
// Welcome to the DSA Playground! 🚀
// Write any JavaScript code below and click Run.

function fibonacci(n) {
  if (n <= 1) return n;
  return fibonacci(n - 1) + fibonacci(n - 2);
}

console.log("Fibonacci(10):", fibonacci(10));

// Try your own code!
const arr = [1, 2, 3, 4, 5];
const doubled = arr.map(x => x * 2);
console.log("Doubled:", doubled);

// Check if a string is a palindrome
function isPalindrome(str) {
  const cleaned = str.toLowerCase().replace(/[^a-z0-9]/g, '');
  return cleaned === cleaned.split('').reverse().join('');
}

console.log("'racecar' is palindrome?", isPalindrome("racecar"));
console.log("'hello' is palindrome?", isPalindrome("hello"));
Output
Click Run to see output