Reverse an array without affecting special characters from geeksforgeeks.com

Reverse an array without affecting special characters

function isAlphabet(x)
{
    return ( (x >= 'A' &&  x <= 'Z') ||
             (x >= 'a' &&  x <= 'z') );
}

function reverse(str)
{
    console.log('INPUT ARRAY ' + str.join(''))

    var r = str.length - 1, l = 0;
    while (l < r)
    {
        if (!isAlphabet(str[l])) // Ignore special characters
        {
          l++;
        }
        else if(!isAlphabet(str[r])) // Ignore special characters
        {
          r--;
        }
        else // Both str[l] and str[r] are not spacial
        {   
            swap(l, r);
            l++;
            r--;
        }
    }
  
  function swap(from , to){
    var temp =  str[from];
    str[from] = str[to];
    str[to] = temp;
  }
  
  console.log('OUTPUT ARRAY ' + str.join(''))
}

var string = 'a!!!b.c.d,e ,f,ghi'
reverse(string.split(''))