Progressive Server-Side Rendering — the key to a faster web page is the technique of sequentially rendering parts of the web page on the server-side and send it to the client in portions without waiting for the entire page to be rendered.”
Progressive Server-Side Rendering (PSSR) is based on the concept of
HTML streaming. PSSR breaks the pages into meaningful components using code splitting. Those pieces of the page are controlled by a separate script, and now we have the opportunity to hydrate them independently based on some priority that we’ve determined earlier.
Let’s take a quick look at how the PSSR works:
- The browser requests the server for the HTML.
- The server makes API requests and renders the critical content first, and sends it to the client.
- The browser parses the HTML and paints it on the screen.
- The server renders the non-critical content and streams it to the browser.
- The browser then parses and paints the non-critical content.
- In the meantime, JS bundles are downloaded and executed in the background, and the browser hydrates interactivity to DOM elements.
PSSR improves your web app’s performance by fetching & rendering the page components in a parallel & prioritized manner. This approach is known as the Progressive Hydration method.
This Progressive hydration method leads to:
- Defer hydration of a component until it comes into view or is needed for user interaction.
- Load content on user interaction(scroll) — a lot faster than CSR and SSR
- Testing shows this can improve TTI.
- A better user experience even in the slow networks.
In addition to that, you can use the critical rendering path approach with PSSR to optimize your application’s performance even more.