@bigfishtv/cockpit/src/utils/scrollUtils.js

import $ from 'jquery'
import _throttle from 'lodash/throttle'

// @refactor to not use jquery and maybe move this to Section component
// and add multiple listeners directly to document? is this method slower/faster?

const $window = $(window)
const $document = $(document)
const listeners = []
export let scroll = $document.scrollTop()

export function addListener(func) {
	if (listeners.indexOf(func) < 0) listeners.push(func)
}

export function removeListener(func) {
	const index = listeners.indexOf(func)
	if (index >= 0) listeners.splice(index, 1)
}

function handleScroll() {
	scroll = $document.scrollTop()
	const windowHeight = $window.height()
	for (let func of listeners) {
		func(scroll, windowHeight)
	}
}

$document.on('scroll', _throttle(handleScroll, 1000 / 20))