Replay vs. Cursor for UI State: Which AI Code Generator Generates Better Results?

TL;DR: Replay, leveraging video analysis and behavior-driven reconstruction, generates more accurate and functional UI code compared to Cursor's reliance on static code analysis and limited UI understanding.

Replay vs. Cursor for UI State: Which AI Code Generator Generates Better Results?#

The promise of AI-powered code generation is tantalizing: rapidly transforming ideas into working UI. But the reality often falls short. Existing tools frequently struggle to accurately capture UI state and user intent, resulting in code that requires significant rework. Two contenders in this space are Replay and Cursor. This article dives deep into a comparison, focusing on how each tool handles UI state and the quality of the resulting code.

Cursor, known for its powerful IDE integration and code generation capabilities, excels at tasks like refactoring and generating code snippets from natural language prompts. However, when it comes to reconstructing UI from existing interfaces, its reliance on static code analysis and limited understanding of user behavior can lead to inaccuracies. Replay, on the other hand, takes a fundamentally different approach. By analyzing video recordings of user interactions, Replay reconstructs UI based on behavior, resulting in more accurate and functional code.

Understanding the Core Differences: Video vs. Static Analysis#

The key differentiator between Replay and Cursor lies in their input and analysis methods:

Cursor operates primarily on existing codebases and natural language prompts. It's adept at understanding code structure and generating new code based on provided context. However, it struggles to accurately infer UI state from code alone, especially in complex applications with dynamic data and intricate user interactions. It's like trying to understand a movie plot by only reading the script – you miss the nuances of the acting, cinematography, and overall direction.

Replay, conversely, analyzes video recordings of users interacting with an existing UI. This "behavior-driven reconstruction" approach allows Replay to capture not only the visual appearance of the UI but also the intent behind user actions. By understanding what the user is trying to achieve, Replay can generate code that accurately reflects the desired UI state and behavior. This is particularly crucial for applications with complex workflows and dynamic data.

Reconstructing a Multi-Page Application: A Practical Example#

Let's consider a scenario: reconstructing a simple e-commerce application with multiple pages (product listing, product detail, shopping cart) from a video recording.

Cursor's Approach#

Using Cursor, you might attempt to generate code by providing prompts like:

"Generate a React component for a product listing page with a grid of product cards." "Generate a React component for a product detail page that displays product information and an 'Add to Cart' button." "Generate a React component for a shopping cart page that displays the items in the cart and a total price."

While Cursor might generate basic components based on these prompts, it would likely struggle with:

• •Maintaining consistent UI state across pages: The shopping cart needs to persist across navigation.
• •Handling dynamic data: Fetching product data from an API or database.
• •Accurately replicating the visual design: Matching the exact layout, styling, and branding of the original application.

The resulting code would likely require significant manual adjustments to achieve the desired functionality and visual fidelity.

Replay's Approach#

With Replay, you simply provide a video recording of a user navigating the e-commerce application. Replay then analyzes the video, identifying UI elements, user interactions (e.g., clicking on a product, adding an item to the cart), and page transitions. Based on this analysis, Replay generates React code that accurately reflects the UI state and behavior observed in the video.

Here's a simplified example of the code Replay might generate for a product detail page:

typescript
// Generated by Replay
import React, { useState, useEffect } from 'react';

const ProductDetail = ({ productId }) => {
  const [product, setProduct] = useState(null);

  useEffect(() => {
    const fetchProduct = async () => {
      const response = await fetch(`/api/products/${productId}`);
      const data = await response.json();
      setProduct(data);
    };

    fetchProduct();
  }, [productId]);

  if (!product) {
    return <div>Loading...</div>;
  }

  return (
    <div>
      <h1>{product.name}</h1>
      <img src={product.image} alt={product.name} />
      <p>{product.description}</p>
      <button onClick={() => addToCart(product)}>Add to Cart</button>
    </div>
  );
};

export default ProductDetail;

This code snippet demonstrates how Replay can automatically generate code that:

• •Fetches product data from an API.
• •Displays product information.
• •Includes an "Add to Cart" button that triggers a function (presumably defined elsewhere) to update the shopping cart state.

Furthermore, Replay can automatically generate code for the shopping cart page, ensuring that the cart state is persisted across navigation and that the total price is calculated correctly.

Key Advantages of Replay's Behavior-Driven Reconstruction#

Replay's video-based approach offers several key advantages over traditional code generation methods:

• •Accurate UI State Capture: Replay directly observes UI state changes in the video, ensuring that the generated code accurately reflects the desired behavior.
• •Understanding User Intent: By analyzing user interactions, Replay can infer the intent behind those actions, resulting in more functional and user-friendly code.
• •Automated Data Binding: Replay can automatically identify data sources and generate code to bind data to UI elements.
• •Multi-Page Application Support: Replay seamlessly handles multi-page applications, tracking navigation and state transitions across pages.
• •Reduced Manual Adjustments: The code generated by Replay typically requires significantly fewer manual adjustments compared to code generated by other tools.
• •Style Injection: Replay can infer and inject styles to the generated code for a closer visual match.

Real-World Use Cases: Where Replay Shines#

Replay is particularly well-suited for the following use cases:

• •Reconstructing legacy applications: Quickly generate code for outdated applications without access to the original source code.
• •Prototyping new features: Rapidly prototype new UI features based on video recordings of user interactions.
• •Creating design mockups: Generate interactive design mockups from video recordings of existing applications.
• •Automating UI testing: Generate automated UI tests based on video recordings of user behavior.
• •Migrating applications to new frameworks: Effortlessly migrate existing applications to new frameworks by recording user interactions and generating code for the target framework.

💡 Pro Tip: When recording video for Replay, ensure smooth, deliberate interactions. Clear navigation and distinct actions lead to better code generation.

Supabase Integration: Simplifying Backend Development#

Replay's Supabase integration further streamlines the development process by automatically generating code for data fetching, storage, and authentication. By analyzing video recordings of user interactions with Supabase-backed applications, Replay can generate code that seamlessly integrates with Supabase services.

📝 Note: Replay's Supabase integration handles common tasks like user authentication, data fetching, and real-time updates, significantly reducing the amount of boilerplate code you need to write.

For example, if a user creates a new account in the video, Replay can generate the necessary code to handle user registration, store user data in Supabase, and authenticate the user. Similarly, if a user updates data in the video, Replay can generate code to update the corresponding data in Supabase.

typescript
// Example of Replay-generated code with Supabase integration
import { supabase } from './supabaseClient';

const createUser = async (email, password) => {
  const { data, error } = await supabase.auth.signUp({
    email: email,
    password: password,
  });

  if (error) {
    console.error("Error creating user:", error.message);
    return null;
  }

  return data.user;
};

Comparison Summary#

⚠️ Warning: Replay requires clear, focused video recordings for optimal results. Avoid rapid, erratic movements during the recording process.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited functionality and paid plans for more advanced features and usage. Check the Replay pricing page for the most up-to-date information.

How is Replay different from v0.dev?#

While both Replay and v0.dev aim to generate UI code, they differ significantly in their approach. v0.dev relies on text prompts to generate code, whereas Replay analyzes video recordings of user interactions. This allows Replay to capture UI state and user intent more accurately, resulting in more functional and user-friendly code. Furthermore, Replay offers features like multi-page application support and Supabase integration, which are not available in v0.dev. Replay understands what users are trying to do, not just what they see.

---

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