Pitfalls

String Reversal in place

for(let i =0; i < Math.floor(str.length/2); i++) 
	[str[i], str[str.length- 1-i]] = [str[str.length- 1-i], str[i]]];

You're attempting to reverse a string in-place using destructuring assignment, which is a great idea in languages like Python or with arrays in JavaScript — but strings are immutable in JavaScript, meaning you cannot modify them directly by index.

This would work if str were an array, but since str[i] is not assignable (because strings are immutable), this will throw an error like:

❌ TypeError: Cannot assign to read only property '0' of string 'hello'

✅ Correct Approach: Convert to Array First

If you want to reverse a string using this kind of logic, convert it to an array first:

function reverseString(str) {
  let arr = str.split('');
  for (let i = 0; i < Math.floor(arr.length / 2); i++) {
    [arr[i], arr[arr.length - 1 - i]] = [arr[arr.length - 1 - i], arr[i]];
  }
  return arr.join('');
}

✅ Or Simply:

function reverseString(str) {
  return str.split('').reverse().join('');
}

Palindrome ignoring case and non-alphanumerics

function isPalindrome(str) {
  // Remove non-alphanumeric characters and convert to lowercase
  const cleaned = str.replace(/[^a-z0-9]/gi, '').toLowerCase();
  
  // Compare cleaned string to its reverse
  return cleaned === cleaned.split('').reverse().join('');
}

OR

function isPalindrome(str) {
  let left = 0;
  let right = str.length - 1;

  while (left < right) {
    // Skip non-alphanumeric on the left
    while (left < right && !isAlphaNumeric(str[left])) left++;
    // Skip non-alphanumeric on the right
    while (left < right && !isAlphaNumeric(str[right])) right--;

    // Compare characters (case-insensitive)
    if (str[left].toLowerCase() !== str[right].toLowerCase()) {
      return false;
    }

    left++;
    right--;
  }

  return true;
}

function isAlphaNumeric(c) {
  const code = c.charCodeAt(0);
  return (
    (code >= 48 && code <= 57) ||  // 0-9
    (code >= 65 && code <= 90) ||  // A-Z
    (code >= 97 && code <= 122)    // a-z
  );
}