It appears that window.webkitNotifications has already been deprecated and removed. However, there's a new API, and it appears to work in the latest version of Firefox as well.
function notifyMe() {
// Let's check if the browser supports notifications
if (!("Notification" in window)) {
alert("This browser does not support desktop notification");
}
// Let's check if the user is okay to get some notification
else if (Notification.permission === "granted") {
// If it's okay let's create a notification
var notification = new Notification("Hi there!");
}
// Otherwise, we need to ask the user for permission
// Note, Chrome does not implement the permission static property
// So we have to check for NOT 'denied' instead of 'default'
else if (Notification.permission !== 'denied') {
Notification.requestPermission(function (permission) {
// Whatever the user answers, we make sure we store the information
if(!('permission' in Notification)) {
Notification.permission = permission;
}
// If the user is okay, let's create a notification
if (permission === "granted") {
var notification = new Notification("Hi there!");
}
});
} else {
alert(`Permission is ${Notification.permission}`);
}
}