fine-fiddle

/*
 * MS Teams lacks a "mark all as read" function, and doing it manually is arduous. 
 * This is the start of userscript to do it automatically. (for teams.microsoft.com)
 * 
 * Teams 'lazy-loads' chats, so click the filter search, then the elipses, and sort by unread. 
 * Next, scroll to the bottom of your unread chats. Then you can run this script.
 */

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));