Edit in JSFiddle

$(function() {
    $.ajaxSetup({
        timeout: 1000,
        error: function(request, status, maybe_an_exception_object) {
            if (status != 'timeout')
                alert('Online')
            else
                alert('Offline')
        }
    });

    // Register listeners
    window.addEventListener("offline", function() {
        $('#globalDiv').hide();
        $("#message").html('WARNING: Internet connection has been lost.');
    });
    window.addEventListener("online", function() {
        $("#message").html('INFO: You are online.');
    });
});

$("#message").html('Wait ...');

<div class="container">
    <h1>Online/Offline</h1>
    <p id="message">
    </p>
</div>