问node.js从error.code和error.errno中提取错误含义

EN

function system_error_description(err_code) {
  if(typeof err_code != "string"
      || err_code.length < 2 
      || err_code[0] != "E") {
    return "Invalid system error code '" + err_code.toString() + "'";
  }
  switch(err_code) {
    case "EACCES":
      return "Permission denied";
    case "EADDRINUSE":
      return "Address already in use";
    case "ECONNREFUSED":
      return "Connection refused";
    case "ECONNRESET":
      return "Connection reset by peer";
    case "EEXIST":
      return "File exists";
    case "EISDIR":
      return "Is a directory";
    case "EMFILE":
      return "Too many open files in system";
    case "ENOENT":
      return "No such file or directory";
    case "ENOTDIR":
      return "Not a directory";
    case "EPERM":
      return "Operation not permitted";
    case "EPIPE":
      return "Broken pipe";
    case "ETIMEDOUT":
      return "Operation timed out";
    default:
      return "System error code '" + err_code + "' not recognized";
  }
}