Legacy JS to TypeScript & React Hooks Helper

Legacy Codebase Refactorer

🟢 100% Free

Convert jQuery, ES5 callbacks, and React Class components to modern TypeScript & Hooks.

100% Client-Side Engine

Preset Mode:

Load Sample:

Legacy Input Code

import React, { useState, useEffect } from 'react';

interface UserProfileProps {
  userId?: string;
  [key: string]: any;
}

export const UserProfile: React.FC<UserProfileProps> = ({ userId }) => {
  const [user, setUser] = useState<any>(null);
  const [loading, setLoading] = useState<any>(true);

  useEffect(() => {
    // Extracted from componentDidMount
    const loadData = async () => {
      try {
        const response = await fetch(`/api/user/${userId}`);
        const result = await response.json();
        // Update state
        setUser(result);
      } catch (error) {
        console.error('Failed to load data:', error);
      }
    };
    loadData();
  }, [userId]);

  return (
    <div className="userprofile-container">
      {/* Refactored Clean JSX */}
      <h1>Profile Details</h1>
    </div>
  );
};

Automate Legacy Code Refactoring Locally

Modernizing an aging codebase is tedious and error-prone. The Legacy Code Refactorer uses an intelligent client-side engine to automatically transform outdated React Class components, jQuery scripts, and ES5 callback chains into clean, modern TypeScript and React Hooks. Best of all, because execution happens entirely in your browser, your proprietary company code is never sent to a third-party server. Pair this utility with our other Developer Tools to accelerate your migration workflows.

Refactoring Capabilities

React Class to Hooks: Instantly converts `componentDidMount`, `this.state`, and class methods into functional components using `useState` and `useEffect`.
jQuery to Vanilla JS: Strips out heavy jQuery dependencies by transforming `$.ajax` to `fetch`, and `$()` selectors to `document.querySelectorAll()`.
Automated Test Generation: Simultaneously scaffolds Jest/Vitest unit testing boundaries for the newly refactored code modules.

Frequently Asked Questions

Why should I refactor legacy code?

Refactoring legacy code improves application performance, reduces technical debt, and ensures compatibility with modern frameworks and build tools. For example, moving from React Classes to Hooks significantly reduces bundle size and improves component reusability.

Is it safe to automate code refactoring?

Automated refactoring is highly effective for structural transformations, but the output should always be reviewed by a human engineer. Our tool provides a detailed "Execution Log" so you can see exactly which rules were applied and automatically generates scaffolding tests to help you verify the logic.

How to use Legacy Codebase Refactorer & Modernizer

1Select your target conversion mode from the preset buttons (e.g., React Class ➔ Hooks, jQuery ➔ Vanilla JS, or Full Auto).
2Paste your legacy JavaScript, jQuery, or React code into the left editor pane.
3The client-side engine will instantly parse the code patterns and output the modernized TypeScript version in the right pane.
4Click the 'Changes' tab to view a detailed breakdown of every structural transformation applied to your code.
5Switch to the 'Jest Unit Tests' tab to copy an auto-generated test suite customized for your newly refactored code.

About Legacy Codebase Refactorer & Modernizer

Get a head start modernizing legacy JavaScript, jQuery and React class components toward TypeScript and Hooks. Rule-based output; always review before shipping.

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Automate Legacy Code Refactoring Locally

Refactoring Capabilities

React Class to Hooks: Instantly converts `componentDidMount`, `this.state`, and class methods into functional components using `useState` and `useEffect`.
jQuery to Vanilla JS: Strips out heavy jQuery dependencies by transforming `$.ajax` to `fetch`, and `$()` selectors to `document.querySelectorAll()`.
Automated Test Generation: Simultaneously scaffolds Jest/Vitest unit testing boundaries for the newly refactored code modules.

Legacy Codebase Refactorer & Modernizer

Legacy Codebase Refactorer

Automate Legacy Code Refactoring Locally

Refactoring Capabilities

Frequently Asked Questions

Why should I refactor legacy code?

Is it safe to automate code refactoring?

How to use Legacy Codebase Refactorer & Modernizer

About Legacy Codebase Refactorer & Modernizer

More Developer Tools

Legacy Codebase Refactorer

Automate Legacy Code Refactoring Locally

Refactoring Capabilities

Frequently Asked Questions

Why should I refactor legacy code?

Is it safe to automate code refactoring?