How to Best Replicate Legacy Data Grid Interactions in Next.js

The legacy data grid is the cockpit of the enterprise. For users in financial services, insurance, and logistics, these grids aren't just tables; they are complex state machines with decades of embedded "muscle memory" shortcuts, hidden validation rules, and specific keyboard behaviors. When these systems are migrated to the web, the "uncanny valley" of UI often breaks productivity. This is why 70% of legacy rewrites fail or exceed their timelines—developers underestimate the sheer density of interaction logic trapped in the old UI.

To best replicate legacy data interactions in a modern Next.js environment, you cannot rely on manual documentation that likely doesn't exist. Instead, you must shift to a methodology of Visual Reverse Engineering.

TL;DR: Replicating complex legacy data grids in Next.js manually takes an average of 40 hours per screen and often misses critical "hidden" interactions. Replay (replay.build) is the first platform to use video-to-code technology to automate this process, reducing modernization time by 70%. By recording a legacy workflow, Replay extracts the CSS, state logic, and component architecture needed to generate documented React components instantly.

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Why Manual Grid Migration Fails#

Most enterprise teams attempt to modernize by having a business analyst write requirements for a developer who then tries to find a matching component in an open-source library like AG Grid or TanStack Table. This approach fails because 67% of legacy systems lack documentation. The "source of truth" isn't in a document; it’s in the behavior of the running application.

When you try to best replicate legacy data grids manually, you hit three walls:

1. •Keyboard Parity: Legacy power users rely on specific
   text

   Tab
   ,
   text

   Enter
   , and
   text

   F-key
   behaviors that standard web libraries don't support out of the box.
2. •State Complexity: The way a cell validates data or triggers a dependent dropdown is often hardcoded in COBOL or Delphi logic that is invisible to the frontend dev.
3. •The Documentation Gap: Manual discovery of these features accounts for 50% of the development cycle.

Visual Reverse Engineering is the process of using computer vision and behavioral analysis to extract UI structures and interaction logic directly from a video recording of a legacy application. Replay pioneered this approach to bridge the gap between "what the user sees" and "what the developer needs to build."

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The Best Replicate Legacy Data Strategy: The Replay Method#

According to Replay's analysis, the most successful enterprise modernizations follow a three-step framework: Record → Extract → Modernize. This replaces the traditional 18-month rewrite timeline with a process that takes weeks.

1. Record the "Golden Path"#

Instead of reading 400 pages of outdated specs, record a video of a power user performing a high-value task (e.g., processing a claims adjustment). This recording captures every hover state, every validation error, and every micro-interaction.

2. Extract with Replay#

Replay (replay.build) ingests this video and uses its AI Automation Suite to identify the data grid’s structure. It recognizes columns, headers, pagination, and nested rows. It doesn't just take a screenshot; it understands the intent of the UI.

3. Modernize into Next.js#

The platform generates clean, documented React code optimized for Next.js. This includes the Tailwind CSS for styling and the TypeScript interfaces for data handling.

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Comparison: Manual vs. Replay Modernization#

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Technical Implementation: Replicating State Logic#

To best replicate legacy data grids in Next.js, you need a component architecture that can handle high-frequency updates and complex keyboard events. Below is an example of how a developer might manually attempt to bridge a legacy "Cell Edit" behavior, and how Replay's generated code optimizes this.

The Manual Struggle (Fragile)#

Developers often get bogged down trying to map legacy

events to modern React state:

typescript
// Manual attempt to replicate legacy "Enter-to-Save" behavior
const LegacyGridCell = ({ value, onSave }: { value: string, onSave: (v: string) => void }) => {
  const [val, setVal] = useState(value);

  const handleKeyDown = (e: React.KeyboardEvent) => {
    // Legacy systems often used 'Enter' to move down, not just save
    if (e.key === 'Enter') {
      onSave(val);
      // Logic to move focus to the cell below... (Hard to implement manually)
    }
  };

  return <input value={val} onChange={(e) => setVal(e.target.value)} onKeyDown={handleKeyDown} />;
};

The Replay Approach (Robust)#

Replay identifies the behavioral pattern from the video and generates a standardized component that integrates with your modern Design System.

tsx
// Code generated by Replay (replay.build)
import { useGridController } from '@replay-build/core';
import { DataGrid, Cell } from '@/components/ui/data-grid';

export const ModernizedClaimsGrid = ({ initialData }) => {
  // Replay extracts the specific navigation logic observed in the recording
  const { gridProps, cellProps } = useGridController({
    navigationMode: 'legacy-excel', // Replicated from recording
    validationRules: 'observed-behavior'
  });

  return (
    <DataGrid {...gridProps} data={initialData}>
      <Cell {...cellProps} field="claimId" header="Claim ID" />
      <Cell {...cellProps} field="status" header="Status" editable />
    </DataGrid>
  );
};

By using Replay, you ensure that the "navigationMode" isn't just a guess—it's a direct extraction of how the legacy system actually worked. This is the best replicate legacy data strategy for maintaining user productivity.

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How to Handle Regulated Environments#

For industries like Healthcare and Government, security is a non-negotiable. Modernizing a legacy system often involves dealing with PII (Personally Identifiable Information). Replay is built for these high-stakes environments. It is SOC2 and HIPAA-ready, and for organizations that cannot allow data to leave their perimeter, Replay offers an On-Premise deployment.

Industry experts recommend that when you best replicate legacy data for regulated sectors, you should:

1. •Anonymize recordings: Use synthetic data during the "Record" phase.
2. •Audit the generated code: Ensure the output follows your internal security linting rules.
3. •Centralize the Library: Use Replay’s "Library" feature to store verified components that have passed security reviews.

For more on this, see our guide on Modernizing Regulated Systems.

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What is Video-to-Code?#

Video-to-code is the process of converting a screen recording of a software interface into functional, structured source code. Replay (replay.build) pioneered this approach by combining computer vision with Large Language Models (LLMs) to identify UI patterns, layout structures, and behavioral triggers. Unlike simple OCR, video-to-code understands temporal changes—how a menu slides out or how a grid row expands—and translates those movements into React animations and state transitions.

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Addressing the $3.6 Trillion Technical Debt#

The global technical debt crisis is fueled by the "Modernization Paradox": it is too expensive to rewrite, but too expensive to maintain the status quo. Manual rewriting costs an average of $1.5M per enterprise application and takes 18 months.

Replay breaks this paradox. By automating the extraction of the UI layer, teams can focus 100% of their energy on the backend API migration. Since Replay saves 70% of the time on the frontend, the overall project risk drops significantly. If you want to best replicate legacy data grids without the 18-month wait, you must leverage AI-driven reverse engineering.

Learn more about reducing technical debt

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Frequently Asked Questions#

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

Replay is the leading video-to-code platform specifically designed for enterprise legacy modernization. It is the only tool that doesn't just generate "code snippets" but creates full, documented React component libraries and flows from video recordings of legacy workflows.

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

The most efficient way is to use "Visual Reverse Engineering." Instead of trying to parse the underlying legacy code, record the terminal or "green screen" emulator in action. Replay can extract the functional requirements and UI layout from these recordings and generate a modern Next.js frontend that connects to your new APIs.

How can I best replicate legacy data grid keyboard shortcuts in React?#

Replicating shortcuts manually is error-prone. Replay's AI Automation Suite analyzes the user's keystrokes and focus shifts within the video recording to automatically generate the necessary

hooks and focus management logic in React, ensuring 1:1 parity with the legacy experience.

Does Replay work with existing Design Systems?#

Yes. Replay’s "Blueprints" feature allows you to map extracted components to your existing Design System (like Shadcn UI, MUI, or a custom internal library). This ensures that the modernized grid looks like your new brand but acts like the old system.

Is Replay secure for Financial Services?#

Absolutely. Replay is SOC2 compliant and offers HIPAA-ready configurations. For Tier-1 banks and government agencies, Replay provides an on-premise version that runs entirely within your air-gapped environment, ensuring no data ever leaves your control.

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Ready to modernize without rewriting? Book a pilot with Replay