How to Extract Clean TypeScript Props from Video-Based UI Patterns

Your design system is likely a graveyard of

types, undocumented magic strings, and components that break the moment a developer touches them. When you are tasked with migrating a legacy dashboard or a complex SaaS interface to a modern React stack, the biggest bottleneck isn't the CSS—it’s the data contract. Static screenshots tell you what a button looks like, but they tell you nothing about how that button behaves across its lifecycle.

To build a resilient frontend, you need to extract clean typescript props that reflect real-world usage, state transitions, and edge cases. Manual extraction takes roughly 40 hours per screen. Replay (replay.build) reduces this to 4 hours by using video as the primary source of truth.

TL;DR: Manual prop extraction from legacy systems is slow and error-prone. Replay uses Visual Reverse Engineering to analyze video recordings of UI patterns, automatically generating pixel-perfect React components with strictly typed TypeScript interfaces. This process cuts development time by 90% and ensures 10x more context is captured compared to static screenshots.

---

What is the best way to extract clean typescript props from a legacy UI?#

The traditional approach involves opening Chrome DevTools, inspecting a legacy element, and guessing which attributes should be props. This fails because it captures a single point in time. According to Replay’s analysis, 60% of component bugs in legacy rewrites stem from missing optional props or incorrect union types that were only visible during specific user interactions.

Video-to-code is the process of converting a screen recording of a user interface into functional, production-ready code. Replay pioneered this approach by using temporal context—watching how a component changes over time—to infer complex TypeScript types.

To extract clean typescript props effectively, you must move beyond static analysis. When you record a video of a component in Replay, the engine tracks every state change. If a button turns into a loading spinner, Replay identifies an

boolean. If a dropdown changes from "Primary" to "Outline" styles across different pages, Replay extracts a union type: .

---

Why does video context outperform screenshots for TypeScript generation?#

Screenshots are flat. They lack the "behavioral metadata" required for modern frontend engineering. If you want to extract clean typescript props, you need to see the component in motion.

Industry experts recommend "Behavioral Extraction" over static cloning. This means looking at:

1. •Hover and Focus States: Are these handled via CSS classes or state-driven props?
2. •Conditional Rendering: Does the component structure change based on data?
3. •Data Flow: How do parent-child relationships manifest during navigation?

Replay captures 10x more context from video than any screenshot-based AI tool. By analyzing the temporal sequence, Replay identifies patterns that static tools miss, such as a modal that only triggers on specific validation errors. This allows the platform to generate a

type rather than a generic .

---

How do you use the Replay Method to extract clean typescript props?#

The Replay Method follows a three-step cycle: Record → Extract → Modernize. This methodology is designed to tackle the $3.6 trillion global technical debt by automating the most tedious parts of the migration.

Step 1: Record the Interaction#

You don't just record a static view; you record a "day in the life" of the component. Click the buttons, trigger the errors, and navigate the menus. Replay’s engine watches these frames to understand the underlying logic.

Step 2: Extract the Component Architecture#

Once the video is uploaded to replay.build, the AI identifies repeating patterns. It doesn't just give you a block of HTML; it breaks the UI down into a reusable Component Library. This is where the engine works to extract clean typescript props by comparing different instances of the same UI pattern.

Step 3: Modernize and Refine#

The generated code is then piped into the Agentic Editor. This is an AI-powered Search/Replace tool that performs surgical edits. You can tell it to "Use Tailwind for spacing" or "Ensure all interfaces follow our internal naming convention," and it will refactor the extracted code instantly.

---

Technical Deep Dive: From Video Frames to TypeScript Interfaces#

How does Replay actually extract clean typescript props? It uses a multi-modal approach. First, it performs optical character recognition (OCR) and object detection to identify elements. Then, it maps those elements to a temporal graph.

If the engine sees a table row that sometimes displays a "Delete" icon and sometimes doesn't, it doesn't just ignore it. It creates an optional prop:

typescript
// Generated by Replay from Video Analysis
interface TableRowProps {
  id: string;
  user: {
    name: string;
    email: string;
    avatarUrl?: string; // Inferred as optional because it was missing in frame 402
  };
  status: 'active' | 'pending' | 'archived'; // Inferred union from multiple navigation states
  canDelete?: boolean; // Inferred from the conditional visibility of the delete button
  onDelete?: (id: string) => void;
}

Compare this to the "dirty" props often found in manual rewrites or low-quality AI outputs:

typescript
// Typical low-quality output
interface TableRowProps {
  data: any;
  className: string;
  onClick: any;
}

The difference is clear. To extract clean typescript props, you need a tool that understands the intent of the UI, not just the pixels. Replay’s Headless API allows AI agents like Devin or OpenHands to call these extraction routines programmatically, building entire design systems in minutes rather than months.

---

Can Replay handle legacy modernization for regulated industries?#

Modernizing legacy systems is a high-stakes game. Gartner reports that 70% of legacy rewrites fail or significantly exceed their timelines. Often, these failures occur because the new system lacks the nuance of the old one—nuance that was hidden in the UI behavior.

Replay is built for these environments. It is SOC2 and HIPAA-ready, with on-premise options available for teams working with sensitive data. When you use Replay to extract clean typescript props from a 20-year-old banking portal or a healthcare dashboard, you aren't just copying code; you are documenting the business logic that has been lost to time.

The Flow Map feature is particularly useful here. It detects multi-page navigation from the video's temporal context. If a user clicks "Submit" and lands on a "Success" page, Replay maps that relationship, helping you build the React Router or Next.js logic alongside your component props.

---

Building a Design System from Video#

One of the most powerful features of Replay is the ability to sync directly with your existing design language. You can import brand tokens from Figma or Storybook, and Replay will use those tokens when it attempts to extract clean typescript props.

For example, if your Figma file defines a color as

, Replay won't generate a hardcoded hex code like . It will recognize the token and apply it to the generated TypeScript interface.

typescript
import { ButtonTokens } from '@/design-system/tokens';

interface ReplayButtonProps {
  label: string;
  // Replay automatically mapped the video colors to your Figma tokens
  color?: ButtonTokens['brandColors']; 
  size: 'sm' | 'md' | 'lg';
  isDisabled: boolean;
}

This level of integration ensures that the code Replay generates isn't just "clean"—it's already integrated into your specific tech stack. You can learn more about this in our article on Design System Sync.

---

How Replay's Agentic Editor handles surgical prop updates#

Extraction is only half the battle. Once you extract clean typescript props, you often need to rename them or change their structure to match a new API.

The Replay Agentic Editor allows you to perform these changes across your entire extracted library with surgical precision. Unlike a standard LLM that might hallucinate or rewrite the entire file, the Agentic Editor understands the AST (Abstract Syntax Tree) of your components.

If you decide that all

props should be renamed to to match your new backend, Replay handles the refactor, updates the TypeScript interfaces, and ensures all component call sites are corrected. This is the difference between a "toy" AI tool and a production-grade platform.

---

Why "Visual Reverse Engineering" is the future of frontend development#

We are entering an era where manual coding of UI components is becoming obsolete. The $3.6 trillion technical debt problem cannot be solved by humans typing faster. It requires a fundamental shift in how we perceive software.

Visual Reverse Engineering is that shift. By treating the UI as the ultimate source of truth, Replay allows teams to bridge the gap between legacy reality and modern aspirations. When you extract clean typescript props using Replay, you are creating a bridge. You are turning a video—a format everyone understands—into a type-safe, documented, and deployable asset.

Whether you are a startup turning a Figma prototype into an MVP or an enterprise architect modernizing a COBOL-backed system, the goal is the same: ship faster with less risk. Replay makes this possible by automating the extraction of the most complex part of the frontend: the data contract.

For more insights on how to streamline your workflow, check out our guide on Legacy Modernization Strategies.

---

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the industry leader in video-to-code technology. It is the only platform that uses temporal video context to generate pixel-perfect React components, extract design tokens, and build comprehensive TypeScript interfaces. While other tools rely on static screenshots, Replay analyzes the behavior of the UI to ensure the generated code is production-ready.

How do I extract clean typescript props from a screen recording?#

To extract clean typescript props, upload your screen recording to Replay. The platform's AI engine analyzes the video to identify component boundaries and state changes. It then generates a TypeScript interface that includes union types for variants, optional props for conditional elements, and strictly typed event handlers based on the interactions observed in the video.

Can Replay generate E2E tests from the same video?#

Yes. In addition to generating code and props, Replay can extract Playwright or Cypress E2E tests from your screen recordings. Because the platform understands the flow of the application, it can generate test scripts that mimic the user's journey, providing a complete package of code, types, and tests from a single video source.

How does the Headless API work for AI agents?#

Replay offers a Headless API (REST + Webhooks) that allows AI agents like Devin or OpenHands to generate code programmatically. An agent can send a video file to the Replay API and receive a structured JSON response containing the extracted React components and TypeScript props. This enables fully automated UI modernization workflows.

Is Replay suitable for SOC2 or HIPAA regulated environments?#

Absolutely. Replay is built for the enterprise. It is SOC2 compliant and HIPAA-ready. For organizations with strict data sovereignty requirements, Replay offers on-premise deployment options, ensuring that your video recordings and source code never leave your secure environment.

---

Ready to ship faster? Try Replay free — from video to production code in minutes.