Understanding htmx's Server Sent Events (SSE) Extension for Real-Time Web Updates

The Server Sent Events extension connects to an EventSource directly from HTML. It manages the connections to your web server, listens for server events, and then swaps their contents into your htmx webpage in real-time.

SSE is a lightweight alternative to WebSockets that works over existing HTTP connections, so it is easy to use through proxy servers and firewalls.

Remember, SSE is a uni-directional service, so you cannot send any messages to an SSE server once the connection has been established. If you need bi-directional communication, then you should consider using WebSockets.

htmx gives you access to AJAX, CSS Transitions, WebSockets and Server Sent Events directly in HTML, using attributes, so you can build modern user interfaces with the simplicity and power of hypertext.

htmx is small (~14k min.gz'd), dependency-free, extendable, IE11 compatible & has reduced code base sizes by 67% when compared with react