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var busybody = require("busybody")

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busybody v1.0.0

Measure express routes speed over time.


Your friendly neighborhood request tracker?



import express from 'express';
import busybody from 'busybody';

const app = express();
const tracker = busybody();


app.get('/stats', (req, res) => {

app.get('/ping', (req, res) => {
  setTimeout(() => res.send('pong'), 100);

app.listen(8080, () => console.log('Server listening'));


  "since": "2016-05-19T21:18:44.362Z",
  "routes": [
      "route": "/ping",
      "count": 4,
      "mean": 127.5,
      "standardDeviation": 25.5,
      "min": 96.3,
      "max": 153.4
      "route": "/stats",
      "count": 4,
      "mean": 1.7,
      "standardDeviation": 1.1,
      "min": 1,
      "max": 3.5


busybody(options) -> tracker

Creates a new tracker. Takes in the following options.

  • step=21600000 - Time between steps in milliseconds. Defaults to 6 hours.
  • window = 4 - Maximum steps to store.
  • maxSize = 500 - Maximum unique paths to store per step, after path sanitization.
  • precision = 2 - Maximum decimals to round to.
  • preFilter(req, res) -> boolean - Custom function to filter tracked requests before they're handled.
  • postFilter(err, req, res) -> boolean - Custom function to filter tracked requests after they're handled.
  • sanitize(req, res) -> string - Custom function to sanitize a url. By default, removes querystring, ids, uuids, and casing.
  • onStep(step) - shortcut for tracker.on('step', fn) (see Events)
  • onExpire(step) - shortcut for tracker.on('expire', fn) (see Events)

busybody.sanitize(req, res) -> string

The default sanitization function. It makes the following transformations to req.originalUrl.

  1. Extract the pathname.
  2. Normalize the pathname.
  3. Replace all numbers with :id.
  4. Replace all uuids with :uuid.
  5. Make everything lowercase.
> /path/../2/something?foo=bar

> /foo/BAR/21/123e4567-e89b-12d3-a456-426655440000

tracker(req, res, next)

Express middleware that should be placed above routes you want to keep stats about.

tracker.getStats(sort = 'mean') -> object

Returns the stats output.

The sort parameter can be count, mean, standardDeviation, min, or max.

tracker.push(path, ms)

Manually track a path and duration.


The middleware returned by busybody is also an EventEmitter that exposes the following events:

  • expire - emitted when a step is about to expire. Passed the expiring step.
  • step - emitted after a new step was created. Passed the new step.


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