ESP8266 LittleFS listFiles as URL

String str;

if (!LittleFS.begin())
{
  Serial.println("LittleFS failed to mount !");
}

Dir dir = LittleFS.openDir("/");

while (dir.next())
{

  String file_name = dir.fileName();

  if (file_name.startsWith("LOG"))
  {

    str += "<a href=\"";
    str += dir.fileName();
    str += "\">";
    str += dir.fileName();
    str += "</a>";
    str += "    ";
    str += dir.fileSize();
    str += "<br>\r\n";

  }

}