Debounce a state change, sustain for the duration by repeated calls.

README.md

Debounce a state change with a sustain.

This is debounce with true|false passed to the callback.

In this example the value of scrolling will be true during the scroll event and for 250ms after.

import sustain from 'sustain';
let scrolling = false;

sustainScrolling = sustain(250, (state) => scrolling = state)

addEventListener('scroll', sustainScrolling)

In this example the value of sustainScrolling.state will reflect whether scrolling is true or false

import { sustainState } from 'sustain';

sustainScrolling = sustain(250)

addEventListener('scroll', sustainScrolling)

The value of sustainState.state can be given by the callback

sustainState(250, (sustained, prevState) =>
  sustained ? { count: prevState.count + 1 } : { count: 0 ))

index.js

import sustain from './sustain'
import sustainState from './sustainState'

export sustain;
export sustainState;

export default sustain;

package.js

{
  "name": "sustain",
  "version": "1.0.0",
  "description": "Sustain a state for a time",
  "main": "index.js",
  "repository": {
    "type": "git",
    "url": "git+https://gist.github.com/05fda32de726ff00a972f75aa5934963.git"
  },
  "keywords": ["debounce", "sustain state"],
  "author": "Evan Schneider",
  "license": "ISC",
  "bugs": {
    "url": "https://gist.github.com/05fda32de726ff00a972f75aa5934963"
  },
  "homepage": "https://gist.github.com/05fda32de726ff00a972f75aa5934963"
}

sus

sustain.js

export default function sustain (duration, toggle) {
    let timeout;

    let cycle = () => {
        cycle.sustain();
        timeout = setTimeout(cycle.release, duration)
    }

    cycle.suspend = () => clearTimeout(timeout);
    cycle.sustain = () => cycle.suspend() + toggle(true);
    cycle.release = () => cycle.suspend() + toggle(false);

    return cycle;
}

sustainState.js

import sustain from './sustain';

export default function sustainState (duration, toggle = (s) => s) {
    let cycle = sustain(duration, (state) => {
        cycle.state = toggle(state, cycle.state);
    });

    return cycle;
}