response-time

What is response-time?

The response-time npm package is a middleware for Node.js that records the response time for HTTP requests. It is typically used with Express.js to measure the time taken to handle requests and send responses, which can be useful for performance monitoring and optimization.

What are response-time's main functionalities?

Basic Usage

This code demonstrates the basic usage of the response-time middleware in an Express.js application. It measures the response time for each HTTP request and adds it to the 'X-Response-Time' header.

const express = require('express');
const responseTime = require('response-time');

const app = express();

// Add the response-time middleware
app.use(responseTime());

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Custom Response Time Header

This code demonstrates how to use the response-time middleware with a custom header. Instead of the default 'X-Response-Time' header, it sets a custom header 'X-Custom-Response-Time' with the response time.

const express = require('express');
const responseTime = require('response-time');

const app = express();

// Add the response-time middleware with a custom header
app.use(responseTime((req, res, time) => {
  res.setHeader('X-Custom-Response-Time', `${time}ms`);
}));

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Logging Response Time

This code demonstrates how to log the response time for each request using the response-time middleware. It logs the HTTP method, URL, and response time to the console.

const express = require('express');
const responseTime = require('response-time');

const app = express();

// Add the response-time middleware with a logging function
app.use(responseTime((req, res, time) => {
  console.log(`Response time for ${req.method} ${req.url}: ${time}ms`);
}));

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Other packages similar to response-time

morgan

Morgan is an HTTP request logger middleware for Node.js. It logs details about incoming requests, including response times, to the console or a file. While it provides more comprehensive logging capabilities compared to response-time, it is not specifically focused on measuring response times.

express-status-monitor

Express Status Monitor is a simple, self-hosted module based on Socket.io and Chart.js to report realtime server metrics for Express-based applications. It provides a web-based dashboard to monitor various metrics, including response times, making it more feature-rich compared to response-time.

prom-client

Prom-client is a Prometheus client for Node.js that allows you to instrument your application with custom metrics, including response times. It provides more flexibility and integration with Prometheus for monitoring and alerting, but requires more setup compared to response-time.

README

response-time

Response time for Node.js servers.

This module creates a middleware that records the response time for requests in HTTP servers. The "response time" is defined here as the elapsed time from when a request enters this middleware to when the headers are written out to the client.

Installation

$ npm install response-time

API

var responseTime = require('response-time')

responseTime([options])

Create a middleware that adds a X-Response-Time header to responses. If you don't want to use this module to automatically set a header, please see the section about responseTime(fn).

Options

The responseTime function accepts an optional options object that may contain any of the following keys:

digits

The fixed number of digits to include in the output, which is always in milliseconds, defaults to 3 (ex: 2.300ms).

header

The name of the header to set, defaults to X-Response-Time.

suffix

Boolean to indicate if units of measurement suffix should be added to the output, defaults to true (ex: 2.300ms vs 2.300).

responseTime(fn)

Create a new middleware that records the response time of a request and makes this available to your own function fn. The fn argument will be invoked as fn(req, res, time), where time is a number in milliseconds.

Examples

express/connect

var express = require('express')
var responseTime = require('response-time')

var app = express()

app.use(responseTime())

app.get('/', function (req, res) {
  res.send('hello, world!')
})

vanilla http server

var finalhandler = require('finalhandler')
var http = require('http')
var responseTime = require('response-time')

// create "middleware"
var _responseTime = responseTime()

http.createServer(function (req, res) {
  var done = finalhandler(req, res)
  _responseTime(req, res, function (err) {
    if (err) return done(err)

    // respond to request
    res.setHeader('content-type', 'text/plain')
    res.end('hello, world!')
  })
})

response time metrics

var express = require('express')
var responseTime = require('response-time')
var StatsD = require('node-statsd')

var app = express()
var stats = new StatsD()

stats.socket.on('error', function (error) {
  console.error(error.stack)
})

app.use(responseTime(function (req, res, time) {
  var stat = (req.method + req.url).toLowerCase()
    .replace(/[:\.]/g, '')
    .replace(/\//g, '_')
  stats.timing(stat, time)
}))

app.get('/', function (req, res) {
  res.send('hello, world!')
})

License

MIT