react-relay-network-layer/es/middleware/perf.js

Network Layer for React Relay and Express (Batch Queries, AuthToken, Logging, Retry)

/* eslint-disable no-console */
export default function performanceMiddleware(opts) {
  const logger = opts && opts.logger || console.log.bind(console, '[RELAY-NETWORK]');
  return next => req => {
    // get query name here, because `req` can be changed after `next()` call
    const query = `${req.relayReqType} ${req.relayReqId}`;
    const start = new Date().getTime();
    return next(req).then(res => {
      const end = new Date().getTime();
      logger(`${query}: ${end - start}ms`);
      return res;
    });
  };
}