Count the number of occurrences of a repeating event per unit of time
npm install frequency-counterCount the number of occurrences of a repeating event per unit of time.


```
npm install frequency-counter --save
Example HTTP server responding with the number of requests per minute (rpm):
`js
const http = require('http')
const Freq = require('frequency-counter')
// if no arguments are given a window of one minute is used
const counter = new Freq()
const server = http.createServer(function (req, res) {
// increment the count
counter.inc()
// return current frequency to client
res.end('rpm: ' + counter.freq() + '\n')
})
server.listen(3000)
`
Initialize the frequency counter. Optionally set a custom window size in
seconds over which the frequency should be calcuated (default: 60).
Track an occurrence by incrementing a counter. Optionally provide the
amount to increment by (default: 1`).
Calculate and return the current frequency.
MIT