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CSR vs. SSR

The debate between Server-Side Rendering (SSR) and Client-Side Rendering (CSR) centers on where the rendering of the user interface happens: on the server or in the user’s browser.

CSR (Client-Side Rendering)

  • How it works: The server sends a minimal HTML page with links to JavaScript files. The browser downloads these files and then dynamically renders the UI using JavaScript.
  • The problem: CSR introduces complexity by creating a two-state problem. The server holds the “source of truth” data, and the client holds a copy of that data to display. Keeping these two states synchronized is challenging. This often requires complex client-side logic and more sophisticated communication protocols. Another pain point is SEO, as search engine crawlers can sometimes struggle to properly index content rendered with CSR.
  • Pros: Rich user experiences (faster interactions after the initial load), separation of concerns (backend focuses on APIs, frontend on UI).
  • Cons: Higher initial load time (as the browser needs to download and execute JavaScript), potential SEO issues, more client-side code, the complexity of managing state synchronization.

SSR (Server-Side Rendering)

  • How it works: The server renders the entire HTML page, including the data, and sends it to the browser. The browser simply displays the received HTML.
  • How it works, improved: HTMX improves on this by only swapping the parts of the DOM that changed, using the server’s response
  • The problem: The traditional SSR approach causes a complete page reload on every interaction, resulting in a noticeable “white flash” or flicker and interrupting the user experience.
  • Pros: Faster initial load time (content is immediately visible), better SEO (search engines can easily crawl the rendered HTML), simpler client-side code (less JavaScript required), a single source of truth on the server.
  • Cons: Slower subsequent interactions (every interaction requires a server request and full page reload - unless improved by HTMX), increased server load.

HTMX as a potential solution

HTMX can address the UX problem of SSR, which is page reloading. HTMX allows selectively updating parts of the page by sending HTML snippets from the server, leading to a smoother user experience without the complexity of CSR. The article also talks about the “HARM stack,” a stack that uses HTMX to solve problems caused by complexity in modern web stacks.

In summary

  • CSR offers rich interactions but introduces client-side complexity.
  • SSR is simpler but historically provided poorer user experiences due to full page reloads.
  • HTMX can offer the simplicity of SSR with a more interactive user experience by selectively updating parts of the page.

References

Page last modified: 2025-05-08 11:32:10