How do you reverse a string in place in JavaScript?

Question

How do you reverse a string in place (or in-place) in JavaScript when it is passed to a function with a return statement, without using built-in functions (.reverse()<

Answer 1

I know that this is an old question that has been well answered, but for my own amusement I wrote the following reverse function and thought I would share it in case it was useful for anyone else. It handles both surrogate pairs and combining marks:

function StringReverse (str)
{
  var charArray = [];
  for (var i = 0; i < str.length; i++)
    {
      if (i+1 < str.length)
        {
          var value = str.charCodeAt(i);
          var nextValue = str.charCodeAt(i+1);
          if (   (   value >= 0xD800 && value <= 0xDBFF
                  && (nextValue & 0xFC00) == 0xDC00) // Surrogate pair)
              || (nextValue >= 0x0300 && nextValue <= 0x036F)) // Combining marks
            {
              charArray.unshift(str.substring(i, i+2));
              i++; // Skip the other half
              continue;
            }
        }

      // Otherwise we just have a rogue surrogate marker or a plain old character.
      charArray.unshift(str[i]);
    }

  return charArray.join('');
}

All props to Mathias, Punycode, and various other references for schooling me on the complexities of character encoding in JavaScript.