https://github.com/begriffs/decaying-accumulator

A number that tends toward zero but can be nudged
https://github.com/begriffs/decaying-accumulator

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A number that tends toward zero but can be nudged

• Host: GitHub
• URL: https://github.com/begriffs/decaying-accumulator
• Owner: begriffs
• Created: 2013-05-07T00:03:19.000Z (almost 13 years ago)
• Default Branch: master
• Last Pushed: 2013-05-17T15:50:07.000Z (almost 13 years ago)
• Last Synced: 2025-02-12T04:05:51.559Z (about 1 year ago)
• Language: JavaScript
• Size: 246 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
## A nudgeable number that tends toward zero

[![Build Status](https://travis-ci.org/begriffs/decaying-accumulator.png)](https://travis-ci.org/begriffs/decaying-accumulator)

In applications such as realtime crowd voting or an audio VU meter, we

want a number which spikes upward but decays to zero over time. This

module captures exactly this, with no extra frills.

### Try [a demo](http://begriffs.github.io/decaying-accumulator/)

    // Create an accumulator that decays in one second

    var DecayingAccumulator = require('DecayingAccumulator'),

      dac = new DecayingAccumulator({decaySpeed: 1000});

    dac.nudge(1);

    // now dac.currentValue() === 1

    ...

    // some time later

    // 0 <= dac.currentValue() < 1

Individual nudges begin to count for less if they "bury the needle." The

`currentValue` method always returns within -1 and 1 inclusive. You can

specify an initial scale when constructing this class.

    new DecayingAccumulator({decaySpeed: 1000, currentScale: 4});

    // now currentValue() === 0.25 after nudge(1)

If nudges have adjusted the scale you can have it reset after a cooldown

period by providing a `cooldownSpeed` argument to the constructor.

## Running tests locally

    npm install

    node_modules/.bin/mocha

(Or `npm install -g mocha` to add it to your path.)