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# response-time
[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Build Status][travis-image]][travis-url]
[![Test Coverage][coveralls-image]][coveralls-url]
[![Gratipay][gratipay-image]][gratipay-url]
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
```sh
$ npm install response-time
```
## API
```js
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)`](#responsetimeoptions).
#### 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
```js
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
```js
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
```js
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](LICENSE)
[npm-image]: https://img.shields.io/npm/v/response-time.svg
[npm-url]: https://npmjs.org/package/response-time
[travis-image]: https://img.shields.io/travis/expressjs/response-time/master.svg
[travis-url]: https://travis-ci.org/expressjs/response-time
[coveralls-image]: https://img.shields.io/coveralls/expressjs/response-time/master.svg
[coveralls-url]: https://coveralls.io/r/expressjs/response-time?branch=master
[downloads-image]: https://img.shields.io/npm/dm/response-time.svg
[downloads-url]: https://npmjs.org/package/response-time
[gratipay-image]: https://img.shields.io/gratipay/dougwilson.svg
[gratipay-url]: https://www.gratipay.com/dougwilson/
|
