It's very simple to display a native notification using JavaScript.
<script>
function showNotification() {
Notification.requestPermission().then(permission => {
if (permission == 'granted') {
new Notification("Example Notification", { body: "The content of the notification." })
}
})
}
</script>
<button onclick="showNotification()">Send Notification</button>
When you click the button, the code will first request the permission to display notifications and then it will display a notification.
The only issue with the above code is that the web app / website needs to be open in order to display the notification.
If you want to send the notifications even when the website is closed you will need to use a more complex stack of technologies (Push API, WebPush, Service Workers, etc.) or a service like Pushpad.