Building SvelteKit Apps from User Story Videos

TL;DR: Stop designing in static tools; reconstruct working SvelteKit UI directly from user story videos with Replay and behavior-driven code generation.

Forget pixel-perfect mockups. The future of UI development isn't about static designs; it's about understanding user behavior. We've all been there: painstakingly crafting designs only to realize users interact with the application in unexpected ways. The problem? Designs are abstractions, not reality. What if you could build directly from real user stories?

That's where Replay comes in. We're pioneering a new approach: Behavior-Driven Reconstruction. Instead of starting with static images or designs, you begin with video. Replay analyzes video recordings of user interactions and uses Gemini to reconstruct fully functional UI components and applications. Think of it as turning user stories directly into working code. Specifically, let's dive into how to build SvelteKit apps using this revolutionary method.

Why Video-to-Code is a Game Changer#

Traditional design-to-code workflows are fundamentally flawed. They rely on interpretations and assumptions, leading to discrepancies between the intended user experience and the final product. Screenshots only capture a single frame in time, missing the crucial context of user actions and intent.

Consider this comparison:

Replay leverages video as the source of truth, capturing the nuances of user behavior that static designs simply miss. This translates to:

• •Faster development cycles: Skip the design handoff and go straight to working code.
• •Improved user experience: Build based on real user interactions, not assumptions.
• •Reduced rework: Catch usability issues early in the development process.
• •More accurate representation of user stories: Translate user journeys directly into code.

Building SvelteKit Apps with Replay: A Step-by-Step Guide#

Let's walk through the process of building a SvelteKit app from a user story video using Replay. We'll focus on a simple example: creating a basic to-do list application.

Step 1: Capture the User Story#

Record a video of yourself (or a user) interacting with a hypothetical to-do list application. This could be a hand-drawn mockup, a prototype in Figma, or even just a verbal description of the desired behavior. The key is to capture the flow: adding tasks, marking them as complete, and deleting them.

💡 Pro Tip: The clearer and more deliberate the user interactions in the video, the better the reconstruction will be. Narrate your actions to provide additional context.

Step 2: Upload and Analyze with Replay#

Upload the video to Replay. Our engine will analyze the video, identifying UI elements, user actions, and the overall flow of the application. This process leverages Gemini's powerful video understanding capabilities to extract meaningful information.

Step 3: Review and Refine the Generated Code#

Replay generates SvelteKit code based on the video analysis. This includes:

• •Svelte components for each UI element (e.g., input field, button, list item).
• •JavaScript logic for handling user interactions (e.g., adding tasks, toggling completion status).
• •Basic styling to match the visual appearance in the video.

Review the generated code and make any necessary refinements. Replay provides a visual editor that allows you to easily adjust the code and see the changes in real-time.

📝 Note: The initial code generation may not be perfect. Replay is designed to provide a strong foundation, but some manual adjustments may be required, especially for complex interactions or custom styling.

Step 4: Integrate with Supabase (Optional)#

Replay seamlessly integrates with Supabase, allowing you to easily persist data and add real-time functionality to your SvelteKit app. If your user story involves data persistence, Replay can automatically generate the necessary Supabase schema and API calls.

To connect to Supabase:

1. •Provide your Supabase URL and API key.
2. •Define the data model for your to-do list (e.g.,
   text

   id
   ,
   text

   task
   ,
   text

   completed
   ).
3. •Replay will generate the necessary SvelteKit endpoints and Supabase queries to create, read, update, and delete tasks.

Step 5: Style Injection for Polish#

While Replay generates basic styling, you'll likely want to customize the appearance of your SvelteKit app to match your brand or design preferences. Replay supports style injection, allowing you to easily add custom CSS or Tailwind classes to the generated components.

For example, to add a custom background color to the to-do list:

svelte
<div class="todo-list" style="background-color: #f0f0f0;">
  <!-- To-do list items -->
</div>

Alternatively, you can use Tailwind CSS:

svelte
<div class="bg-gray-100 p-4 rounded-md">
  <!-- To-do list items -->
</div>

Step 6: Product Flow Maps for Understanding#

Replay goes beyond simple code generation. It also provides product flow maps, visualizing the user's journey through the application. This helps you understand how users interact with your app and identify potential areas for improvement.

The product flow map shows:

• •The sequence of user actions.
• •The UI elements involved in each action.
• •The transitions between different states of the application.

This visual representation is invaluable for optimizing the user experience and ensuring that your SvelteKit app meets the needs of your users.

A Concrete Code Example#

Let's say Replay generated the following Svelte component for displaying a to-do list item:

svelte
<!-- src/lib/TodoItem.svelte -->
<script>
  export let task;
  export let completed;

  const toggleComplete = () => {
    completed = !completed;
  };
</script>

<div class="todo-item">
  <input type="checkbox" bind:checked={completed} on:click={toggleComplete} />
  <span class:completed={completed}>{task}</span>
</div>

<style>
  .todo-item {
    display: flex;
    align-items: center;
    padding: 0.5rem;
    border-bottom: 1px solid #ccc;
  }

  .completed {
    text-decoration: line-through;
    color: #888;
  }
</style>

This component displays a to-do item with a checkbox and a label. The

function updates the status when the checkbox is clicked. The class applies a line-through style to completed tasks.

To use this component in your main SvelteKit page:

svelte
<!-- src/routes/+page.svelte -->
<script>
  import TodoItem from '$lib/TodoItem.svelte';

  let todos = [
    { id: 1, task: 'Learn SvelteKit', completed: false },
    { id: 2, task: 'Build a to-do list', completed: true },
    { id: 3, task: 'Deploy to production', completed: false }
  ];
</script>

<h1>My To-Do List</h1>

{#each todos as todo (todo.id)}
  <TodoItem task={todo.task} completed={todo.completed} />
{/each}

This code iterates over the

array and renders a component for each task.

Challenging Conventional Wisdom#

The traditional approach to UI development often involves a lengthy process of design, prototyping, and handoff. This can lead to delays, miscommunications, and ultimately, a product that doesn't quite meet the needs of its users.

Replay challenges this conventional wisdom by:

• •Eliminating the need for static designs: Start with real user behavior, not abstract representations.
• •Automating code generation: Reduce the amount of manual coding required.
• •Facilitating collaboration: Provide a shared understanding of the user experience.

By embracing behavior-driven reconstruction, you can build SvelteKit apps that are more user-friendly, more efficient, and more aligned with the needs of your users.

⚠️ Warning: Replay is not a replacement for skilled developers. It's a powerful tool that can augment your workflow and accelerate development, but it requires human oversight and refinement.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited usage. Paid plans are available for more extensive use and access to advanced features. Check our pricing page for details.

How is Replay different from v0.dev?#

While both tools aim to accelerate UI development, Replay distinguishes itself by using video as the primary input. This allows Replay to capture user behavior and intent, leading to more accurate and user-centric code generation. v0.dev, in contrast, typically relies on text prompts or design files.

What types of videos work best with Replay?#

Videos with clear user interactions and minimal distractions work best. Narrating your actions can also improve the accuracy of the reconstruction.

What frameworks does Replay support?#

Currently, Replay supports React, Vue, and SvelteKit. We are actively working on adding support for other frameworks.

Can Replay handle complex UI interactions?#

Replay is capable of handling a wide range of UI interactions, but complex interactions may require some manual refinement of the generated code.

---

Ready to try behavior-driven code generation? Get started with Replay - transform any video into working code in seconds.