Hacky changes to Sentral Education's Sickbay Register Screen. Requires something like https://github.com/Ruud14/Page-Manipulator.

register.js

const config = {
    cats: false
}

///

let catImage;
let lastResults;

injection = async () => {
    const list = document.querySelector("#incursions-list");

    if (list === null) {
        console.log("No table found, dipping out.");
        return;
    }
    
    const secondList = document.querySelectorAll("tbody")[1].querySelector("tr");

    console.log("Injecting sick bay register custom code");
    
    removeButtons();
    
    document.querySelector("#scan-slip-print-container").remove();
    
    if (config.cats && secondList.style.display !== "none") {
        secondList.querySelector("div").textContent += ". Have a cat instead!";
        
        const p = document.createElement("p");
        catImage = document.createElement("img");
        
        img.style.width = "25%";
        
        p.appendChild(img);
        secondList.querySelector("div").appendChild(p);
    }
    
    updateColsAndRows(list);
};

updateColsAndRows = (list) => {
    const headersToRemove = [1, 6, 7, 8];
    const headerParent = document.querySelector("thead").querySelector("tr");
    const headers = headerParent.querySelectorAll("th");
    const optionHeader = document.createElement("th");
    const quickActionsHeader = document.createElement("th");

    headersToRemove.forEach(el => headers[el].remove());
    
    headers[5].textContent = "Times";    
    headers[10].textContent = "🗑"
    
    optionHeader.textContent = "Notifs";
    quickActionsHeader.textContent = "⚡";
    
    headerParent.appendChild(optionHeader);
    headerParent.insertBefore(quickActionsHeader, headerParent.childNodes[2]);

    for (var i = 0, row; row = list.rows[i]; i++) {
        const notifsCell = row.insertCell();
        const colsToRemove = [];
        const colIndexsToRemove = [1, 6, 7, 8];
        
        let quickActionLinks;

        notifsCell.innerHTML = `<td><span class="icon icon-spin icon-spinner searchIndicator"></span></td>`;
    
        for (var j = 0, col; col = row.cells[j]; j++) {
            if (colIndexsToRemove.contains(j)) colsToRemove.push(col);
            
            const link = col.querySelector("a");
            const button = col.querySelector("button");
            const menu = col.querySelector(".dropdown-menu");
            
            if (col.contains(link) && !link.contains(link.querySelector("span")) && link.href.slice(-1) !== "#") {
                const searchTerm = "student/";
                const student = link.href.slice(link.href.indexOf(searchTerm) + searchTerm.length).split("/")[0];

                quickActionLinks = `
                    <a href="/attendance/administration/student/${student}" target="_blank">📅</a>
                    <a href="/health/student/${student}/sickbay" target="_blank">📋</a>
                `;
            }
            
            if (j === 5) {
                const start = convertTime12to24(col.textContent.trim());
                
                if (row.cells[6].querySelectorAll("a").length) {
                    col.textContent = getDuration(start);
                } else {
                    const end = convertTime12to24(row.cells[6].textContent.trim());
                    
                    col.innerHTML = `<td>${start} - ${end}<p>${getDuration(start, end)}</p></td>`
                }
            }
            
            if (col.contains(menu)) {
                const remove = menu.querySelectorAll("li")[3].querySelector("a");
                
                remove.className = "remove-sickbay-entry-btn pointer btn btn-danger btn-small";
                remove.innerHTML = '<span class="icon icon-trash"></span>';
               
                col.querySelector(".btn-group").replaceWith(remove);
            }
            
            if (col.contains(button)) {
                button.remove();
            }
        }
        
        colsToRemove.forEach(col => col.remove());
        
        const quickActionsCell = row.insertCell(1);
        
        quickActionsCell.innerHTML = quickActionLinks;
    
        updateRow(row, notifsCell);
    }
}

updateRow = async (row, notifsCell) => {
    const response = await fetch(row.cells[0].querySelector("a").href.replace("edit", "view"));
    const responseData = await response;
    
    if (responseData.status != 200) return;
    
    const parser = new DOMParser();
    const body = await responseData.text();
    const doc = parser.parseFromString(body, "text/html");
    const notiContainer = doc.querySelector("#notification-container");
    const notifications = notiContainer.querySelector(".span8").innerHTML.replace(/\s/g, "").split("<br>").filter(n => n);
    
    let notis = [];
    
    notifications.forEach(function (value) {
        switch (value) {
            case "Phone":
                notis.push("📱");
                break;
                
            case "PushNotification":
                notis.push("🔔");
                break;
                
            default:
                break;
        }
    });
    
    if (notis.length > 0) {
        notifsCell.innerHTML = `<td>${notis.sort().join("")}</td>`;
    } else {
        notifsCell.innerHTML = `<td>❌</td>`;
    }
}

const removeButtons = () => {
    const mainControls = document.querySelector(".content-box-controls");
    
    if (mainControls === null) return;
    
    const mainButton = mainControls.querySelector("button");
    
    if (!mainButton) return;
    
    mainButton.remove();
    
    const controls = document.querySelector(".content-box-footer").querySelector(".controls");
    
    if (controls === null) return;
    
    const button = controls.querySelector("button");
    
    if (!button) return;
    
    button.remove();
}

const getDuration = (start, end = null) => {
    const pastDate = new Date();

    pastDate.setHours(...start.split(":"));
    
    let tempTime;
    
    if (end !== null) {
        const checkOutTime = new Date();

        checkOutTime.setHours(...end.split(":"));
        
        tempTime = msToTime(checkOutTime.getTime() - pastDate.getTime());
    } else {
        tempTime = msToTime(new Date().getTime() - pastDate.getTime());
    }
    
    return tempTime;
}

const convertTime12to24 = (time12h) => {
    const [time, modifier] = [time12h.substring(0, time12h.length -2), time12h.slice(-2)];
    let [hours, minutes] = time.split(":");
    
    if (hours === "12") hours = "00";
    
    if (modifier === "pm") hours = parseInt(hours, 10) + 12;
    
    return `${hours}:${minutes}`;
}

const msToTime = (duration) => {
    let seconds = Math.floor((duration / 1000) % 60);
    let minutes = Math.floor((duration / (1000 * 60)) % 60);
    let hours = Math.floor((duration / (1000 * 60 * 60)) % 24);
    
    if (hours === 0) {
        hours = "";
    } else {
        hours += " hours, ";
    }
    
    if (minutes === 0) {
        minutes = "";
    } else {
        minutes += " minutes";
    }
    
    if (seconds === 0) {
        seconds = "";
    } else if (minutes === "") {
        seconds += " seconds";
    } else {
        seconds = `, ${seconds} seconds`;
    }
    
    return hours + minutes + seconds;
}

const getCatUrl = () => img.src = "https://cataas.com/c?" + new Date().getTime();

injection();