How to use logfmt

function configureMiddlewares(app) {
 app.use(helmet());
 app.use(bodyParser.json());
 app.use(bodyParser.urlencoded({ extended: false }));
 app.use(logfmt.requestLogger());
}

server.listen(5000, () => {
 logfmt.log({ "start": "running server",
        "address": server.address().address,
        "port": server.address().port,
        "osrm-dataset": process.env.OSRM_GRAPH
       });
});

router.post("/", (req, res) => {
 if (!req.body.coordinates) {
  return res.status(422).json({ error: "Missing coordinates" });
 }

 const osrm = req.app.get("osrm");
 const options = {
  coordinates: req.body.coordinates,
  sources: req.body.sources,
  destinations: req.body.destinations
 };

 if (!req.body.sources || !req.body.destinations) {
  delete options.sources;
  delete options.destinations;
 }

 try {
  osrm.table(options, (err, result) => {
   if (err) {
    return res.status(422).json({ error: err.message });
   }
   return res.json(result);
  });
 } catch (err) {
  logfmt.error(new Error(err.message));
  return res.status(500).json({ error: err.message });
 }
});

 ? { ...flat }
 : { ...flat, level, message }
const string = logfmt.stringify(ctx)

 });
} catch (err) {
 logfmt.error(new Error(err.message));
 return res.status(500).json({ error: err.message });

var flat = flatten(data, { delimiter: delimiter });
var ctx = NODE_ENV != 'production' ? _extends({}, flat) : _extends({}, flat, { level: level, message: message });
var string = logfmt.stringify(ctx);