It will close all the message boxes that are automatically added to the bottom left of the LinkedIn page.
// ==UserScript==
// @name LinkedIn: No Messages Boxes
// @namespace https://fred.dev
// @match https://www.linkedin.com/*
// @grant none
// @version 1.0
// @author Frédéric Harper
// @description It will close all the message boxes that are automatically added to the bottom left of the LinkedIn page.
// @license MIT
// ==/UserScript==
window.addEventListener('load', function() {
//HTMLCollection: list item 0 is for a new message (even if not visible), 1 is for the messaging feature (cannot be closed)
const msgBox = document.getElementsByClassName("msg-overlay-bubble-header__control");
//Closing them instead or removing the HTML element so they don't reappear when you reopen LinkedIn or on new pages
for (var i = 2; i < msgBox.length; i++) {
msgBox[i].click();
}
//Removing the messaging box since it cannot be closed
document.getElementById("msg-overlay").remove();
}, false);