JSFiddle - React, Tailwind, and code Playground

HTML

<div id="status">User is online</div>

JavaScript

function updateOnlineStatus()
{
   console.log("User is online");
}

function updateOfflineStatus()
{
    console.log("User is offline");
}

window.addEventListener('online',  updateOnlineStatus);
window.addEventListener('offline', updateOfflineStatus);