fps-emitter/README.md

fps-emitter

Measures the FPS (frames per second) of the current page and emits the result whenever it changes, as an EventEmitter. Designed to be run in the browser.

2.8kB minified+gzipped.

Install

Via npm:

npm install fps-emitter

Or via npmcdn:

<script src="https://npmcdn.com/fps-emitter/dist/fps-emitter.min.js"></script>

Usage

var FpsEmitter = require('fps-emitter')
var fps = new FpsEmitter()

// Get the current FPS, as an integer between 0 and 60:
var currentFps = fps.get()

// Or get notified whenever it changes:
fps.on('update', function (newFps) {
   console.log('FPS is: ', newFps)
})

Update interval

By default, samples are collected every 1000 milliseconds. You can change this either in the constructor or via a runtime API:

var fps = new FpsEmitter(2000); // Update every 2000 milliseconds, from the start

fps.setUpdateInterval(2000); // Change the update interval at runtime

EventEmitter

The FpsEmitter object is an EventEmitter that only emits one event, 'update'. Standard idioms like on(), .once(), and removeListener() all apply.

Debug vs production mode

Once you call the constructor (new FpsEmitter()), it starts tracking the global FPS using requestAnimationFrame(). Simply measuring the FPS has the potential to cause slowdowns, so you may want to disable it in production:

if (DEBUG_MODE) {
  var fps = new FpsEmitter()
  // etc.
} else {
  // do nothing
}

Testing

npm install
npm test