Modern SPA Development: Implementing New Features in Inertia 2.0

Prerequisites

To follow this guide, you should have a solid grasp of Laravel routing and controllers. You should also be comfortable with at least one frontend framework and understand how props are passed from the server to the client. Familiarity with the basic Inertia request lifecycle is recommended.

Key Libraries & Tools

• InertiaJS Core: The primary bridge for managing state between PHP and JavaScript.
• Svelte/Vue/React Adapter: Framework-specific libraries that provide hooks and components like usePoll and WhenVisible.
• Laravel: The backend engine responsible for data fetching and routing.

Code Walkthrough: Deferred Props

One of the most powerful performance features is the ability to defer heavy props. Instead of forcing the user to wait for a slow database query to finish before the initial page render, you can load the shell of the page immediately.

// In your Laravel Controller
return inertia('Dashboard', [
    'user' => $request->user(),
    'stats' => inertia()->defer(fn () => Stats::get())
]);

By wrapping the stats prop in the inertia()->defer function, Inertia skips this data during the initial request. On the client side, you can handle the loading state gracefully:

<script>
  export let stats;
</script>

{#if stats}
  <StatsTable data={stats} />
{:else}
  <LoadingSpinner />
{/if}

Syntax Notes: Intelligent Polling and Prefetching

Inertia 2.0 introduces the usePoll helper, which simplifies refreshing data. Instead of manual setInterval logic, you can define a polling interval directly in your component. Additionally, the prefetch attribute on links allows you to anticipate user navigation. By adding prefetch to a <Link>, Inertia fetches the page data and caches it for a set duration, making the transition feel instantaneous when the user finally clicks.

Practical Examples: Lazy Loading with Visibility

The WhenVisible component is a game-changer for long-scrolling dashboards. Instead of loading every data point on page load, you can wrap expensive components so they only trigger a server request when they enter the viewport.

<WhenVisible data="extraDetails" buffer={300}>
  <ExpensiveComponent data={extraDetails} />
  <div slot="fallback">Loading more...</div>
</WhenVisible>

Tips & Gotchas

• Grouping Defers: You can group deferred props by passing a string as a second argument to defer(). This ensures related data loads together rather than triggering multiple sequential flashes.
• Cache Management: When using link prefetching, be mindful of data staleness. Use the caching options to ensure users aren't seeing hours-old data just because it was prefetched earlier.