Replay for Deno: Building Full-Stack UIs from Video

TL;DR: Replay leverages video analysis and Gemini to automatically generate complete, full-stack Deno applications, offering a faster and more intuitive UI development workflow than traditional methods.

The "screenshot-to-code" promise has always felt…hollow. Static images lack the critical context of user intent. What if you could build UIs from video, capturing not just the visual design but also the underlying user behavior? That's the power of behavior-driven reconstruction.

Deno: A Modern Runtime, A Modern Approach#

Deno, the secure runtime for JavaScript and TypeScript, is rapidly gaining traction as a modern alternative to Node.js. Its built-in security features, TypeScript support, and module management make it a compelling choice for building scalable and maintainable applications. But even with Deno's advantages, UI development can still be time-consuming.

Enter Replay.

Replay analyzes video recordings of user interactions, leveraging Gemini to understand the underlying behavior and automatically generate working code. This includes not just the front-end UI components, but also the necessary backend logic, data models, and API integrations, all tailored for Deno.

The Problem with Traditional UI Development#

Traditional UI development often involves a tedious cycle of:

1. •Designing mockups in tools like Figma or Sketch.
2. •Translating those designs into code.
3. •Writing backend logic to handle user interactions.
4. •Connecting the front-end and back-end.
5. •Testing and iterating.

This process is prone to errors, requires significant manual effort, and can be a major bottleneck in the development lifecycle. Screenshot-to-code tools offer a marginal improvement, but they only address the visual aspect and fail to capture the dynamic nature of user interactions.

Replay: Behavior-Driven Reconstruction for Deno#

Replay revolutionizes UI development by treating video as the source of truth. By analyzing user behavior within the video, Replay can automatically generate:

• •Front-end UI components: React components with Tailwind CSS styling, based on the visual design and user interactions in the video.
• •Back-end logic: Deno functions to handle user events, data validation, and API calls.
• •Data models: TypeScript interfaces and Supabase database schemas to represent the data used in the application.
• •API integrations: Automatically generated API endpoints using Deno's built-in HTTP server.
• •Product Flow Maps: Visual representation of the user's journey through the application based on the video recording

Key Features#

• •Multi-page Generation: Replay can generate entire multi-page applications from a single video recording.
• •Supabase Integration: Seamless integration with Supabase for data storage and authentication.
• •Style Injection: Inject custom styles to fine-tune the look and feel of the generated UI.
• •Product Flow Maps: Visualize the user flow within the application, making it easier to understand and optimize the user experience.

Replay vs. Traditional Methods#

The following table illustrates the key differences between Replay and traditional UI development methods:

Building a Deno Application with Replay: A Step-by-Step Guide#

Here's how you can use Replay to build a full-stack Deno application from video:

Step 1: Capture a Video Recording#

Record a video of yourself interacting with a UI mockup or a similar application. Make sure to demonstrate all the key features and user flows you want to implement.

💡 Pro Tip: Speak clearly while recording, describing your actions. This will help Replay better understand your intent.

Step 2: Upload the Video to Replay#

Upload the video recording to the Replay platform. Replay will automatically analyze the video and generate the corresponding code.

Step 3: Review and Customize the Generated Code#

Replay provides a visual editor where you can review and customize the generated code. You can:

• •Edit the React components.
• •Modify the Deno functions.
• •Adjust the Supabase schema.
• •Add custom styles.

Step 4: Deploy Your Deno Application#

Once you're satisfied with the generated code, you can deploy your Deno application to a hosting provider like Deno Deploy or Fly.io.

Code Example: Generated Deno API Endpoint#

Here's an example of a Deno API endpoint that Replay might generate from a video recording:

typescript
// deno-lint-ignore-file
import { serve } from "https://deno.land/std@0.168.0/http/server.ts";
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2';

// Initialize Supabase client (replace with your actual credentials)
const supabaseUrl = Deno.env.get('SUPABASE_URL') || '';
const supabaseKey = Deno.env.get('SUPABASE_ANON_KEY') || '';
const supabase = createClient(supabaseUrl, supabaseKey);

async function handleRequest(request: Request): Promise<Response> {
  const { pathname } = new URL(request.url);

  if (pathname === "/api/submitForm" && request.method === "POST") {
    try {
      const body = await request.json();
      const { data, error } = await supabase
        .from('form_submissions')
        .insert([ body ]);

      if (error) {
        console.error("Supabase error:", error);
        return new Response(JSON.stringify({ error: "Failed to submit form" }), {
          status: 500,
          headers: { "Content-Type": "application/json" },
        });
      }

      return new Response(JSON.stringify({ message: "Form submitted successfully!", data }), {
        status: 200,
        headers: { "Content-Type": "application/json" },
      });
    } catch (e) {
      console.error("Server error:", e);
      return new Response(JSON.stringify({ error: "Internal server error" }), {
        status: 500,
        headers: { "Content-Type": "application/json" },
      });
    }
  }

  return new Response("Not Found", { status: 404 });
}

console.log("Server listening on port 8000");
serve(handleRequest, { port: 8000 });

This code demonstrates how Replay can automatically generate a Deno API endpoint that handles form submissions and stores the data in a Supabase database.

📝 Note: The actual code generated by Replay will vary depending on the complexity of the video recording and the user interactions demonstrated.

Code Example: React Component#

typescript
import React, { useState } from 'react';

interface FormData {
  name: string;
  email: string;
  message: string;
}

const ContactForm: React.FC = () => {
  const [formData, setFormData] = useState<FormData>({
    name: '',
    email: '',
    message: '',
  });

  const handleChange = (e: React.ChangeEvent<HTMLInputElement | HTMLTextAreaElement>) => {
    setFormData({ ...formData, [e.target.name]: e.target.value });
  };

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();

    try {
      const response = await fetch('/api/submitForm', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(formData),
      });

      if (response.ok) {
        alert('Form submitted successfully!');
        setFormData({ name: '', email: '', message: '' }); // Reset form
      } else {
        alert('Failed to submit form.');
      }
    } catch (error) {
      console.error('Error submitting form:', error);
      alert('An error occurred while submitting the form.');
    }
  };

  return (
    <form onSubmit={handleSubmit} className="max-w-md mx-auto mt-8">
      <div className="mb-4">
        <label htmlFor="name" className="block text-gray-700 text-sm font-bold mb-2">Name:</label>
        <input
          type="text"
          id="name"
          name="name"
          value={formData.name}
          onChange={handleChange}
          className="shadow appearance-none border rounded w-full py-2 px-3 text-gray-700 leading-tight focus:outline-none focus:shadow-outline"
          required
        />
      </div>
      <div className="mb-4">
        <label htmlFor="email" className="block text-gray-700 text-sm font-bold mb-2">Email:</label>
        <input
          type="email"
          id="email"
          name="email"
          value={formData.email}
          onChange={handleChange}
          className="shadow appearance-none border rounded w-full py-2 px-3 text-gray-700 leading-tight focus:outline-none focus:shadow-outline"
          required
        />
      </div>
      <div className="mb-6">
        <label htmlFor="message" className="block text-gray-700 text-sm font-bold mb-2">Message:</label>
        <textarea
          id="message"
          name="message"
          value={formData.message}
          onChange={handleChange}
          className="shadow appearance-none border rounded w-full py-2 px-3 text-gray-700 leading-tight focus:outline-none focus:shadow-outline"
          rows={5}
          required
        ></textarea>
      </div>
      <div className="flex items-center justify-between">
        <button className="bg-blue-500 hover:bg-blue-700 text-white font-bold py-2 px-4 rounded focus:outline-none focus:shadow-outline" type="submit">
          Submit
        </button>
      </div>
    </form>
  );
};

export default ContactForm;

⚠️ Warning: Ensure you configure the Supabase client with your actual project URL and API key for the code to function correctly.

Benefits of Using Replay for Deno Development#

• •Increased Development Speed: Automate the generation of UI components, backend logic, and API integrations.
• •Improved Accuracy: Reduce errors by generating code directly from user behavior.
• •Enhanced Collaboration: Share video recordings and generated code with your team for easier collaboration.
• •Reduced Costs: Save time and resources by automating the UI development process.
• •Better User Experience: Build UIs that are tailored to user behavior, resulting in a better user experience.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited features and usage. Paid plans are available for more advanced features and higher usage limits.

How is Replay different from v0.dev?#

While both tools aim to accelerate UI development, Replay uniquely leverages video input to capture user behavior. V0.dev relies on text prompts, which can be less intuitive and require more manual refinement. Replay's behavior-driven approach results in more accurate and functional code generation.

What types of applications can I build with Replay?#

Replay can be used to build a wide range of applications, including web applications, mobile apps, and desktop applications. The only requirement is that you can record a video of yourself interacting with the UI.

What if Replay generates incorrect code?#

Replay provides a visual editor where you can review and customize the generated code. You can also provide feedback to Replay to help improve its accuracy.

Does Replay support other backend frameworks besides Deno?#

Currently, Replay primarily focuses on Deno for backend generation. However, support for other backend frameworks may be added in the future.

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