Open all unread messages button for OpenU messages system

Open_all_unread_messages_OpenU.js

// ==UserScript==
// @name         Open all unread messages button for OpenU messages system
// @version      0.1
// @description  adding "Mark all as read" button in the messages system
// @author       Roey
// @match        https://sheilta.apps.openu.ac.il/Main/Messages/*
// @license       MIT
// ==/UserScript==

(function() {
    let place = document.querySelectorAll(".search-summary")[0]
    let button = document.createElement('button')
    button.innerHTML = "Open all unread messages"
    button.onclick = OpenAll
    place.appendChild(button)

    function OpenAll(zEvent){
        let x = document.getElementsByClassName("panel-heading unread-message");
        let i;
        for (i=0; i<x.length;i++){
            let j = x[i].getElementsByClassName("collapsed")[0];
            j.click()
        }
    }

})();