code: function lengthBytesUTF32(str) {
    var len = 0;
    for (var i = 0; i < str.length; ++i) {
      // Gotcha: charCodeAt returns a 16-bit word that is a UTF-16 encoded code unit, not a Unicode code point of the character! We must decode the string to UTF-32 to the heap.
      // See http://unicode.org/faq/utf_bom.html#utf16-3
      var codeUnit = str.charCodeAt(i);
      if (codeUnit >= 0xD800 && codeUnit <= 0xDFFF) ++i; // possibly a lead surrogate, so skip over the tail surrogate.
      len += 4;
    }
  
    return len;
  }
docs: Returns the number of bytes the given Javascript string takes if encoded as a UTF16 byte array, EXCLUDING the null terminator byte.