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
This is a Node.js module available through the
npm registry. Installation is done using the
npm install command:
$ 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!')
})
