Middleware to measure request duration for express using the Performance Timing API.

expressRequestDurationMiddleware.js

const { performance } = require('perf_hooks');
const express = require('express');

const expressRequestDurationMiddleware = (req, res, next) => {
  performance.mark('request.start');
  
  const end = res.end;
  res.end = (...args) => {
    performance.mark('request.end');

    performance.measure('request', 'request.start', 'request.end');
    const measure = performance.getEntriesByName('request')[0];

    console.log(`Duration: ${measure.duration}ms\n`);

    performance.clearMeasures('request');
    performance.clearMarks('request.start');
    performance.clearMarks('request.end');

    end.apply(res, args);
  };
  
  next();
}

// example usage:
const app = express();
app.use(expressRequestDurationMiddleware);