Rocket.Chat/app/ui-message/client/popup/customMessagePopups.js

import { ReactiveVar } from 'meteor/reactive-var';
import { Tracker } from 'meteor/tracker';

export const customMessagePopups = new ReactiveVar([]);

const nonReactiveGetFunc = () => Tracker.nonreactive(() => customMessagePopups.get());

export const addMessagePopup = (configGetter, name) => {
	customMessagePopups.set([
		...nonReactiveGetFunc(),
		{
			configGetter,
			name,
		},
	]);
};

export const removeMessagePopup = (popupName) => {
	const customMessagePopupsList = nonReactiveGetFunc();
	const element = customMessagePopupsList.findIndex(({ name }) => name === popupName);
	if (element < 0) {
		return;
	}
	const listWithRemovedElement = [
		...customMessagePopupsList.slice(0, element),
		...customMessagePopupsList.slice(element + 1, customMessagePopupsList.length),
	];
	customMessagePopups.set([...listWithRemovedElement]);
};