@bigfishtv/cockpit/es/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?

var $window = $(window);
var $document = $(document);
var listeners = [];
export var scroll = $document.scrollTop();

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

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

function handleScroll() {
	scroll = $document.scrollTop();
	var windowHeight = $window.height();
	for (var _iterator = listeners, _isArray = Array.isArray(_iterator), _i = 0, _iterator = _isArray ? _iterator : _iterator[Symbol.iterator]();;) {
		var _ref;

		if (_isArray) {
			if (_i >= _iterator.length) break;
			_ref = _iterator[_i++];
		} else {
			_i = _iterator.next();
			if (_i.done) break;
			_ref = _i.value;
		}

		var func = _ref;

		func(scroll, windowHeight);
	}
}

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