Have you ever noticed that Facebook can detect users' zoom-in level and dynamically add a .hidden_elem classname to hide the .fbChatSidebar? (See attachments below)
I've done some research on this feature and came across a GitHub repository called detect-zoom, but it appears there are still issues, especially in the latest versions of FF & Chrome.
I'm really intrigued by how Facebook accomplishes this with JavaScript. I've tested it myself on the latest browsers and Facebook seems to detect and hide the sidebar at the correct zoom level.
Does anyone have insights into how they implement this feature? Any possible solutions would be greatly appreciated.
Thank you.