HTML over WebSockets: real-time SPAs with barely any JavaScript

HTML over WebSockets is an alternative approach to building single-page applications where the server sends pre-rendered HTML directly to the client through a persistent WebSocket connection, rather than serving JSON that the browser must assemble. This pattern, pioneered by Phoenix LiveView and now implemented in various frameworks, consolidates all rendering logic on the backend in a single language, eliminating the need for separate frontend and backend codebases or API contracts. The approach enables real-time, bidirectional communication while requiring minimal JavaScript on the client side, focusing instead on establishing the WebSocket channel and placing received HTML in the appropriate locations.