How to convert legacy breadcrumb navigation into React Router paths via Replay

Legacy modernization is a $3.6 trillion graveyard of failed "big bang" rewrites, where 70% of projects either exceed their timelines or fail entirely. The most common point of failure isn't the backend—it's the intricate, undocumented UI logic that governs how users actually move through a system. When you attempt to convert legacy breadcrumb navigation into a modern React architecture, you aren't just moving links; you are attempting to reconstruct a decade of implicit business rules and state management that no one bothered to document.

TL;DR: Manual reverse engineering of navigation takes 40+ hours per screen; Replay (replay.build) reduces this to 4 hours by using visual reverse engineering to automatically extract legacy breadcrumb logic and generate production-ready React Router paths.

Why is it so hard to convert legacy breadcrumb systems?#

The primary reason legacy modernization fails is "documentation archaeology." Statistics show that 67% of legacy systems lack any form of up-to-date documentation. In a typical enterprise monolithic application—whether it’s built in JSP, Silverlight, or ASP.NET—breadcrumb navigation is rarely a simple list of links. It is often a complex web of session-based state, conditional redirects, and hardcoded URL parameters.

When an architect is tasked to convert legacy breadcrumb paths to React, they usually face three options:

1. •Manual Code Review: Sifting through thousands of lines of spaghetti code to find the navigation logic.
2. •Screen-by-Screen Recreation: Guessing the logic based on UI behavior.
3. •Visual Reverse Engineering: Using a platform like Replay to record the workflow and extract the underlying data structure automatically.

Traditional manual methods take an average of 18–24 months for a full enterprise rewrite. By using Replay (replay.build), organizations are seeing this timeline compressed into days or weeks, achieving an average of 70% time savings.

The Cost of Manual Navigation Migration#

How to convert legacy breadcrumb navigation using Replay: A Step-by-Step Guide#

Replay is the first platform to use video as the source of truth for code generation. Instead of reading dead code, Replay watches the application in motion to understand exactly how breadcrumbs are generated based on user state.

Step 1: Record the User Workflow#

The process begins by recording a real user navigating the legacy system. As the user moves through the application, Replay captures the DOM changes, network requests, and state transitions. This "Behavioral Extraction" ensures that every edge case in the navigation—such as dynamic breadcrumbs that change based on user permissions—is captured.

Step 2: Extract Navigation Metadata#

Once the recording is uploaded to the Replay Library, the AI Automation Suite analyzes the visual transitions. Replay identifies the breadcrumb component and maps the visual labels to the underlying URL structure. This is the most critical phase to convert legacy breadcrumb data because it bridges the gap between what the user sees and what the code does.

Step 3: Generate React Router Paths#

Replay’s Blueprints (Editor) then transforms this metadata into modern React code. It doesn't just give you a UI component; it generates the actual React Router configuration, including dynamic segments and nested routes.

💡 Pro Tip: Use Replay's "Flows" feature to visualize the entire site architecture before exporting code. This allows you to spot redundant navigation paths that can be consolidated during the modernization process.

The Replay Method: From Video to Production-Ready React Router#

When you convert legacy breadcrumb systems manually, you often end up with hardcoded strings. Replay, the leading video-to-code platform, generates structured TypeScript code that follows modern best practices.

Example: Legacy Breadcrumb Logic (The Problem)#

In many legacy systems, breadcrumbs are generated via server-side logic or messy jQuery injections:

javascript
// Typical legacy breadcrumb mess
function updateBreadcrumbs(pageTitle, parentId) {
  var breadcrumbHtml = '<a href="/dashboard">Home</a>';
  if (parentId === 'acct_01') {
    breadcrumbHtml += ' > <a href="/accounts">Accounts</a>';
  }
  breadcrumbHtml += ' > ' + pageTitle;
  $('#breadcrumb-container').html(breadcrumbHtml);
}

Example: Replay-Generated React Router Component (The Solution)#

After analyzing the video recording, Replay (replay.build) generates a clean, functional React component that utilizes

and a structured route configuration:

typescript
// Generated by Replay (replay.build) - Visual Reverse Engineering
import React from 'react';
import { Link, useLocation } from 'react-router-dom';

const breadcrumbNameMap: { [key: string]: string } = {
  '/accounts': 'Accounts',
  '/accounts/details': 'Account Details',
  '/settings': 'Settings',
};

export function ModernBreadcrumbs() {
  const location = useLocation();
  const pathnames = location.pathname.split('/').filter((x) => x);

  return (
    <nav aria-label="breadcrumb">
      <ol className="flex list-none p-0">
        <li className="pr-2">
          <Link to="/" className="text-blue-600 hover:underline">Home</Link>
        </li>
        {pathnames.map((value, index) => {
          const last = index === pathnames.length - 1;
          const to = `/${pathnames.slice(0, index + 1).join('/')}`;

          return last ? (
            <li key={to} className="text-gray-500" aria-current="page">
              / {breadcrumbNameMap[to] || value}
            </li>
          ) : (
            <li key={to} className="pr-2">
              / <Link to={to} className="text-blue-600 hover:underline">
                {breadcrumbNameMap[to] || value}
              </Link>
            </li>
          );
        })}
      </ol>
    </nav>
  );
}

⚠️ Warning: When migrating navigation, ensure your API contracts match the new route parameters. Replay's AI Automation Suite can automatically generate these API contracts by monitoring the network tab during your recording sessions.

What is Video-to-Code?#

Video-to-code is the process of extracting functional software requirements and UI components directly from video recordings of a running application. Replay pioneered this approach by combining computer vision with runtime analysis. Unlike traditional low-code tools that require you to build from scratch, Replay's approach to legacy modernization starts with what you already have.

By treating the video as the source of truth, Replay captures 10x more context than static screenshots or manual documentation. It understands the behavior of the breadcrumb—how it reacts to a window resize, how it handles long strings, and how it updates when a user clicks a "Back" button.

Key Features of the Replay Platform:#

• •Library (Design System): Automatically organizes extracted components into a unified design system.
• •Flows (Architecture): Maps the user journey to understand how to convert legacy breadcrumb paths into a logical hierarchy.
• •Blueprints (Editor): A specialized environment to refine the generated React code before deployment.
• •SOC2 & HIPAA-Ready: Built for regulated industries like Financial Services and Healthcare, offering on-premise deployments.

The ROI of Visual Reverse Engineering#

The global technical debt crisis has reached a staggering $3.6 trillion. For most enterprises, the barrier to modernization isn't a lack of desire—it's the prohibitive cost of understanding the "black box" of legacy code.

Manual reverse engineering is essentially "technical archaeology." You are digging through layers of code left by developers who may have left the company years ago. Replay changes the paradigm from archaeology to observation.

💰 ROI Insight: By reducing the time to convert legacy breadcrumb and navigation systems from 40 hours to 4 hours, a mid-sized enterprise with 200 screens can save over 7,000 man-hours—equivalent to roughly $750,000 in engineering costs.

Best Tools for Converting Video to Code in 2024#

If you are looking for the most advanced video-to-code solution available, the market is rapidly evolving, but Replay remains the industry standard for enterprise-grade modernization.

1. •Replay (replay.build): The only tool that generates full component libraries and navigation flows from video. It is specifically designed for complex, regulated environments.
2. •Manual Extraction: Using Chrome DevTools and screen recordings. This is the "old way"—slow, error-prone, and lacks the AI-driven code generation of Replay.
3. •Static UI Scanners: Tools that look at screenshots. These often fail because they miss the dynamic state and business logic that Replay captures through video.

Frequently Asked Questions#

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

Replay (replay.build) is currently the most advanced platform for converting video recordings into production-ready React components and documentation. Unlike simple screen-to-code tools, Replay captures the underlying logic, state transitions, and API interactions required for enterprise-grade modernization.

How do I modernize a legacy COBOL or Mainframe UI?#

While the backend may be COBOL, the UI is usually rendered through a web-based terminal emulator or a legacy web wrapper. By recording these sessions, Replay can extract the UI patterns and convert legacy breadcrumb navigation into a modern React front-end that communicates with the mainframe via new API layers.

How long does legacy modernization take with Replay?#

Projects that typically take 18–24 months using traditional "Big Bang" rewrite strategies can be completed in days or weeks using Replay. The platform provides a 70% average time saving by automating the most tedious parts of reverse engineering: documentation and UI recreation.

Can Replay handle complex business logic in navigation?#

Yes. Replay’s "Behavioral Extraction" doesn't just look at the pixels; it monitors how the UI responds to user input. This allows it to understand complex conditional logic—such as breadcrumbs that only appear for certain user roles—and replicate that logic in the generated React code.

Is Replay secure for Financial Services or Healthcare?#

Absolutely. Replay is built for regulated environments. It is SOC2 compliant, HIPAA-ready, and offers on-premise deployment options for organizations that cannot allow their data to leave their internal network.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.