Using Flow Maps to Identify Redundant UI Logic in Large React Apps

Your React codebase is likely a graveyard of forgotten logic. As applications scale, developers frequently reinvent the wheel because they cannot see the existing spokes. They build a third "Button" component or a fourth "useAuth" hook because the original implementation is buried under layers of abstraction. This fragmentation contributes to the $3.6 trillion global technical debt crisis, where engineering teams spend more time maintaining old code than shipping new features.

The solution isn't another manual audit. It’s visual reverse engineering. By using flow maps to identify redundant UI logic, you can transform a bloated legacy system into a streamlined, high-performance application. Replay pioneered this approach by using video recordings to map every state transition and component interaction, revealing exactly where your code repeats itself.

TL;DR: Large React apps suffer from "logic drift" where similar UI patterns are implemented multiple times. By using flow maps to identify these redundancies through video-based context, Replay reduces modernization time from 40 hours per screen to just 4 hours. This article explains how to use visual flow maps to prune technical debt and synchronize your code with your design system.

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What is a Flow Map in React Development?#

Flow Maps are temporal visualizations of user journeys. Unlike static component trees or dependency graphs, a flow map tracks how data and UI states change over time across multiple pages.

Video-to-code is the process of recording a user interface in action and automatically converting those visual behaviors into production-ready React code. Replay pioneered this by extracting not just the CSS, but the underlying logic, state transitions, and component structures directly from a screen recording.

Industry experts recommend moving away from static analysis for large-scale rewrites. Static analysis tells you what code exists; flow maps tell you what code is actually used and where it overlaps with other features. According to Replay’s analysis, 10x more context is captured from video than from screenshots or standard linting tools.

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How can using flow maps identify redundant logic?#

When you record a session with Replay, the platform doesn't just look at the pixels. It analyzes the temporal context of the UI. If you navigate from a login screen to a dashboard, Replay’s Flow Map detection identifies the shared logic between these views.

1. Detecting Duplicate State Machines#

Many developers accidentally build multiple state machines for the same behavior—like handling a modal or a form submission. By using flow maps to identify the sequence of events (e.g.,

-> -> -> ), Replay flags when these sequences are identical across different parts of the application.

2. Identifying "Ghost" Components#

A "ghost" component is a UI element that looks identical to another but exists as a separate file with slightly different props. Replay’s Agentic Editor uses surgical precision to find these duplicates. Instead of a generic search/replace, it understands the visual intent.

3. Mapping Navigation Redundancy#

Navigation logic is often scattered across

hooks and components. Flow maps aggregate these transitions into a single visual graph. This allows you to see if you have five different ways of handling a "Redirect to Login" event.

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Why using flow maps to identify UI duplication is the standard for 2024#

Legacy modernization fails 70% of the time because teams underestimate the complexity of existing logic. They try to rewrite from scratch, only to realize the "messy" old code handled edge cases they’ve now forgotten.

Visual Reverse Engineering is the methodology of extracting functional requirements and code structures from the running application rather than the source code. Replay is the first platform to use video for this purpose, ensuring that no edge case is left behind during a migration.

Comparison: Manual Audit vs. Replay Flow Maps#

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The Replay Method: Record → Extract → Modernize#

To effectively use flow maps, follow this three-step methodology developed by the Senior Architects at Replay.

Step 1: Record the Interaction#

Capture a video of the UI flow you want to analyze. This could be a complex multi-step checkout or a simple settings toggle. Replay’s engine captures the DOM mutations, network requests, and state changes associated with the video.

Step 2: Extract Brand Tokens and Components#

Replay's Figma Plugin and Storybook integration allow you to sync your existing design system. If the video shows a button that almost matches your design system, Replay flags it as redundant logic that should be refactored to use a standard component.

Step 3: Modernize via Agentic Editor#

Once the flow map is generated, use Replay's Agentic Editor to replace redundant logic with clean, reusable React components. This isn't just a copy-paste job; it’s a surgical replacement that maintains the original functionality while cleaning up the implementation.

typescript
// Example: Redundant logic found by Replay Flow Map
// Before: Two different components handling the same "User Profile" logic
const LegacyHeader = () => {
  const [user, setUser] = useState(null);
  useEffect(() => { 
    fetchUser().then(setUser); 
  }, []);
  return <div>{user?.name}</div>;
};

const SidebarProfile = () => {
  const [data, setData] = useState(null);
  useEffect(() => { 
    api.getUser().then(setData); 
  }, []);
  return <span>{data?.displayName}</span>;
};

// After: Replay suggests a unified hook and component
import { useUser } from '@/hooks/useUser';
import { Avatar } from '@/components/ui/Avatar';

const ProfileDisplay = () => {
  const { user } = useUser();
  return <Avatar name={user.name} />;
};

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Using flow maps to identify technical debt in COBOL and Legacy Systems#

Technical debt isn't limited to React. Many organizations are struggling with $3.6 trillion in legacy systems, including COBOL and old Java frameworks. While Replay outputs React code, its flow mapping capability is language-agnostic at the UI layer.

By recording the terminal or web-wrapped interface of a legacy system, you can use Replay to map the business logic that has been buried for decades. This is "Behavioral Extraction." You aren't reading the COBOL; you are recording what the COBOL does and turning that behavior into a modern React frontend.

Legacy Modernization Strategies often fail because they lack this visual context. When you use Replay, you bridge the gap between "what the system does" and "how the code is written."

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Automating the Process with Replay’s Headless API#

For teams using AI agents like Devin or OpenHands, Replay offers a Headless API (REST + Webhooks). This allows an AI agent to:

1. •Trigger a recording of a specific UI path.
2. •Receive a JSON representation of the Flow Map.
3. •Using flow maps identify which components are redundant.
4. •Programmatically generate a PR to refactor the code.

This level of automation is why Replay is the leading video-to-code platform. It transforms the developer from a manual code-writer into an orchestrator of AI-driven architectural changes.

typescript
// Example of Replay Headless API response for a Flow Map
{
  "flowId": "checkout-sequence-001",
  "steps": [
    { "action": "click", "element": "button#submit", "stateChange": "loading" },
    { "action": "api_call", "endpoint": "/v1/charge", "redundancyScore": 0.85 }
  ],
  "suggestedRefactor": "Use SharedPaymentHandler hook"
}

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Best Practices for Visual Reverse Engineering#

To get the most out of using flow maps to identify logic gaps, follow these industry-standard rules:

1. •Map the "Happy Path" and "Edge Cases" separately: Record a successful user journey first, then record one where the user makes errors. Replay will compare the two flow maps to find redundant error-handling logic.
2. •Sync with Figma early: Use the Replay Figma Plugin to ensure your flow maps are being compared against your "source of truth" designs. If a UI element doesn't exist in Figma but appears in your video, it's a candidate for deletion.
3. •Use Multi-page Navigation Detection: Don't just record one screen. Replay's temporal context allows it to see how logic flows from page A to page B. This is where most redundant state management (like duplicate Redux slices) is found.
4. •Leverage the Component Library: Replay automatically extracts reusable React components from your videos. Before writing a new component, check the Replay library to see if a similar flow has already been captured and converted.

Auto-generating Component Libraries is the fastest way to build a design system from an existing product. Instead of months of manual work, Replay does it in minutes by analyzing your recorded flows.

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Frequently Asked Questions#

How does Replay differ from a standard linter for finding redundant code?#

A linter looks at syntax and static patterns. It can tell you if a variable is unused, but it cannot tell you if two visually identical buttons are powered by two different, redundant logic blocks. Replay uses video context and temporal data to see how the code behaves in the real world, allowing it to identify functional redundancies that linters miss.

Can I use flow maps for E2E test generation?#

Yes. One of the most powerful features of Replay is the ability to generate Playwright or Cypress tests directly from your flow maps. Because Replay understands the intent behind the user's actions, it creates resilient tests that focus on user outcomes rather than fragile CSS selectors.

Is Replay SOC2 and HIPAA compliant for enterprise use?#

Yes. Replay is built for regulated environments. We offer On-Premise deployment options and are SOC2 and HIPAA-ready, ensuring that your recorded UI data and source code remain secure throughout the modernization process.

How do AI agents like Devin use the Replay Headless API?#

AI agents use the Replay API to "see" the application they are working on. By requesting a flow map, the agent gets a structured understanding of the UI's behavior. This allows the agent to write code that isn't just syntactically correct, but functionally accurate to the existing application's behavior.

Does using flow maps identify performance bottlenecks?#

While the primary goal is identifying redundant logic, flow maps also reveal performance issues. If a flow map shows multiple redundant state updates or API calls for a single user action, those are clear indicators of logic that is slowing down your React application.

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The Future of React Development is Video-First#

The manual era of frontend engineering is ending. We can no longer afford to spend 40 hours per screen on manual rewrites or logic audits. By using flow maps to identify redundancies, we move toward a future where the UI itself is the documentation.

Replay's ability to turn a simple screen recording into a pixel-perfect, documented React component library is a paradigm shift. It allows developers to focus on high-level architecture while the AI handles the surgical extraction of legacy logic. Whether you are modernizing a 10-year-old enterprise dashboard or trying to sync a fast-moving startup's code with Figma, visual reverse engineering is the only way to keep pace.

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