🖼️ Virtual DOM: Declarative Rendering with In-Memory Diffing

React maintains an idealized representation of the UI in memory, often called the Virtual DOM (VDOM). In this model, your React component tree is represented by lightweight JavaScript objects (React elements) rather than direct DOM nodes. When your state or props change, React computes a new virtual DOM and reconciles it with the previous one to determine what real DOM updates are needed. This diffing process lets React batch and minimize expensive DOM operations. In the React docs:

“The virtual DOM (VDOM) is a programming concept where an ideal, or ‘virtual’, representation of a UI is kept in memory and synced with the ‘real’ DOM… This process is called reconciliation.”

By abstracting the DOM updates, React lets you write code declaratively (“tell React what the UI should be”) while it handles the imperative work (“React makes sure the DOM matches that state”). Because JavaScript object updates are much faster than raw DOM manipulation, React can compute changes offscreen and apply only the necessary updates to the real DOM. In practice, a JSX expression compiles into a React element – a plain object with keys like type, props, and children. On each update, React compares the new element objects with the old ones (using component type and keys) and keeps, moves, or removes DOM nodes as needed.

📝 JSX and React Elements: From Syntax to Objects

React’s JSX syntax is just syntactic sugar that ultimately becomes calls to React.createElement(...). For example, JSX like <h1>Hello</h1> is compiled (by Babel) into React.createElement("h1", null, "Hello"). Each call produces a React element – a JS object describing that element. React elements are immutable descriptors of the UI. A simplified element object looks like:

{ 
  $$typeof: Symbol(react.element), 
  type: 'h1', 
  props: { children: 'Hello', className: 'title' }, 
  key: null, 
  ref: null 
}

React elements may also represent component types (functions or classes) and can contain nested children, keyed lists, etc.

When you update state, React “re-renders” by calling your components (or functions) and producing a new tree of these element objects. React then diffs the old vs new trees:

• It assumes elements of different types produce completely different subtrees (so it will tear down and rebuild those nodes).

• It uses key props to match corresponding items in lists.

As one write-up describes, “Whenever something changes, React tries to compare the previous object with the current and decides what to keep, discard and re-create.” In other words, JSX → createElement gives objects, and React’s reconciliation steps determine the minimal set of DOM updates needed to align the UI with those objects.

⚙️ React Fiber, Rendering & Reconciliation

React’s Fiber architecture is its internal reconciliation engine (since React 16). Think of the Fiber tree as a linked data structure of “work units” corresponding to your component tree. Fiber’s headline feature is incremental and prioritized rendering. In the render phase, React traverses your tree of components (via your render() methods or function bodies) and creates/updates the Fiber nodes and the virtual DOM. This phase builds a “work-in-progress” tree and figures out what changed, without touching the real DOM yet.

Key points about Fiber:

• Render Phase (Reconciliation): React creates or updates fiber nodes for each element, computes the diff, and prepares a list of updates. This phase is interruptible: React can pause, yield control (to keep the UI responsive), and resume work. It uses a priority scheduler to update urgent changes (like user input) first. Importantly, no DOM mutations happen yet.

• Commit Phase: Once the diff is ready, React enters the commit phase to apply all changes to the real DOM synchronously. In this phase React applies the updates (inserts, updates, or removes actual DOM nodes) and invokes lifecycle methods or effect callbacks.

These phases ensure React does most heavy work (diffing) off-DOM and only syncs with the browser when ready. By design, reconciliation (diffing) and rendering are separate concerns: the former figures out what should change (per-component, in virtual DOM), and the latter (ReactDOM or React Native renderer) actually updates the target environment. This separation even allows React to target different platforms (browser DOM vs native) with the same core algorithm.

📋 Rendering Steps (Trigger → Render → Commit)

In practice, any React update goes through three steps:

1. Trigger: React begins an update because the root component was mounted, or state/props changed. (e.g. calling root.render(<App/>) or setState/useState).

2. Render (Reconciliation): React calls your components’ render functions (or executes function components) to produce a new element tree. It recursively descends into children, building a fresh virtual DOM and Fiber tree. React then diffs this new tree against the previous one to determine changes.

3. Commit: React applies the changes: it updates the real DOM via minimal operations and runs any queued effects or lifecycles.

⏱️ Component Lifecycle (Mount, Update, Unmount)

Each component (whether class or function with Hooks) goes through mount → update(s) → unmount phases, during which side-effects may run.

Class Components

• constructor()

• render()

• componentDidMount() (after initial commit)

• shouldComponentUpdate()

• componentDidUpdate()

• componentWillUnmount()

Function Components (via Hooks)

• useEffect(() => { ... }, []) → mount effect

• useEffect(() => { ... }, [dep]) → update effect

• return () => { ... } inside useEffect → cleanup on unmount

Function components don’t have an instance or lifecyle methods, but React still manages mount/update/unmount. The Hooks system provides a hook into these stages. useEffect behaves like componentDidMount + componentDidUpdate, and its return value behaves like componentWillUnmount.

⚖️ Class vs Function Components

Key differences in how they work internally and how you write them:

• Syntax and State:
  Class: this.state = { ... } + this.setState()
  Function: const [state, setState] = useState(...)

• Lifecycle and Effects:
  Class: lifecycle methods (componentDidMount, etc.)
  Function: useEffect, useLayoutEffect, useRef, etc.

• Boilerplate and Readability:
  Function components are generally more concise and less error-prone. They avoid this binding issues, and logic can be split across multiple hooks.

• Concurrent Features Compatibility:
  New React features (e.g. Suspense, transitions) are designed with function components in mind.

🧰 Hook Classification for Migration Clarity

As you prepare to transition from class components to functional ones, understanding Hooks is non-negotiable. They’re the modern gateway to managing state, effects, and performance in React.

Let’s look at Hooks through two lenses: what they do and how complex/important they are during development and interviews. This classification helps map them to class lifecycle equivalents and identify when each is appropriate.

🧭 Classification by Meaning

🗂️ State Management Hooks

• useState – Add local component state.

• useContext – Share values across the tree without prop drilling.

• useReducer – Handle complex state logic with reducers (Redux-style).

🔁 Side Effect Hooks

• useEffect – Run side effects after render (e.g., fetches, subscriptions).

• useLayoutEffect – Run effects before the browser paints.

• useInsertionEffect – Inject styles or other low-level layout changes before all layout effects.

• useImperativeHandle – Customize exposed refs with forwardRef.

⚡ Performance Optimization Hooks

• useMemo – Memoize expensive calculations.

• useCallback – Memoize function instances between renders.

• useDeferredValue – Defer updates for low-priority state.

• useTransition – Mark parts of updates as non-urgent.

📦 Reference and Mutable Access Hooks

• useRef – Persist a mutable value across renders (e.g., DOM refs).

• useId – Generate unique IDs across renders/server.

• useSyncExternalStore – Subscribe to external sources (e.g., global state or stores).

🧮 Classification by Complexity, Lifecycle, and Importance

💡 Note: Don’t worry if this list feels overwhelming. You’ll rarely use all of them. Start with the basics (useState, useEffect, useContext) and grow from there as your app demands more power or precision.

By classifying Hooks this way, you'll have a mental map for deciding what to use, when—and how it compares to the lifecycle methods you're migrating from. In future articles, we’ll walk you through mapping class lifecycles to function hooks with side-by-side code samples and caveats.

🚀 Putting It All Together

React’s rendering pipeline:

• JSX → transformed into React elements (objects)

• Fiber builds a virtual DOM tree and diffs it against the previous tree

• Commit Phase applies updates to the real DOM and runs side effects

By understanding these internals, you'll be better equipped to migrate class components, create efficient functional components, and visualize how your code interacts with React's rendering lifecycle.🎯 Key Takeaway: Class and function components feed into the same reconciliation engine. Migrating from one to the other means shifting syntax and lifecycle logic, not the rendering model. Know the internals, and your migrations will be precise, elegant, and future-proof.

Welcome back! If you've been following our series, you'll recall that our earlier articles were aimed at architects and managers planning large-scale React migrations. This article marks a shift—now we're diving deeper into the technical aspects for developers who will carry out the actual migration.

This article is the technical introduction to React migration. It lays the theoretical groundwork necessary for developers to deeply understand how React works—before any code is modified. The series will be split into two parts:

• Theoretical articles: These explain internal mechanics, architecture, and concepts every developer should understand before migrating.

• Practical articles: These will walk you through actual code transformations, refactoring patterns, and edge cases you’ll encounter.

As mentors and software craftsmen, our goal is to help you not just change code, but do it with clarity, confidence, and long-term quality. This guide is here to equip you with the knowledge you’ll need to build a successful migration—without unnecessary headaches.

React is a well-documented JavaScript libraries, and there are countless tutorials and courses online. Our goal is not to repeat these materials but to provide you with specific insights needed for a successful migration. We'll refer to external resources when necessary, but we'll focus on practical understanding, offering you the tools and mental models that truly assist during migration work.

📖 Key Terminology and Concepts

Before diving deeper, let's clarify some crucial terms you'll encounter:

• Fiber: React’s internal architecture for incremental rendering and reconciliation.

• Reconciler: Determines what changes React needs to apply.

• Scheduler: Decides when those changes should be executed.

🧩 React’s Core: Components & Lifecycle

At its heart, React applications are built from components—reusable blocks of UI that encapsulate their own logic and appearance. Before diving into class vs. functional components, it's essential to grasp React’s general lifecycle and how it handles components internally.

🔄 React's Three Core Steps

React’s operation involves three fundamental phases:

1. Trigger: Something initiates a component render (a state change, prop change, or context update, first render).

2. Render: React calculates the changes by invoking your components. This is a pure computation step—it builds a virtual DOM tree but does not touch the browser DOM yet.

“Rendering” is React calling your components.

3. Commit: React applies these changes to the actual DOM. This includes updating the DOM, running refs, and flushing layout effects. Passive effects (useEffect) run after painting.

📚 Resource: React Docs – Render and Commit

This design allows React to batch updates, defer low-priority work, and minimize reflows and repaints—especially important in React 18 with concurrent features.

🛠️ Component Lifecycle Classification

The lifecycle of React components can be classified in many ways. However, to clearly understand components—regardless of whether they're classes or functions—we simplify it into three main phases:

• Mounting: The initial phase of creation and insertion into the DOM.

• Updating: Reacting to changes (state, props, or context) and re-rendering.

• Unmounting: Removal from the DOM and necessary cleanup.

Think of this lifecycle as stages of an organism's life: birth, growth, reproduction, and death—each with specific responsibilities and tasks.

🔍 Class vs. Functional Components Overview

Both class and functional components coexist seamlessly within React, but there are important distinctions, especially in how each interacts with React’s latest features.

• Class Components: Defined using ES6 classes. React creates an instance, stores it in a Fiber node, and manages lifecycle via methods like componentDidMount or componentWillUnmount.

• Functional Components: Defined as pure functions. They don’t have an instance. Instead, React keeps a hooks list on the Fiber node to manage state (useState, useEffect, etc.).

⚠️ Functional components with Hooks are now the preferred style in the React ecosystem.

🚫 Class components cannot use Hooks and may not support future features like Server Components.

Understanding how these two models are implemented internally helps you:

• Translate lifecycle logic accurately.

• Understand performance behavior.

• Make confident architectural decisions during migration.

🧑‍💻 Example Snippets

Class Component:

class Greeting extends React.Component {
  state = { name: 'John' };
  componentDidMount() {
    console.log('Component mounted!');
  }
  render() {
    return <h1>Hello, {this.state.name}</h1>;
  }
}

Functional Component:

function Greeting() {
  const [name, setName] = useState('John');
  useEffect(() => {
    console.log('Component mounted!');
  }, []);

  return <h1>Hello, {name}</h1>;
}

🎯 Migration Best Practices

When migrating to functional components and Hooks, follow these React-recommended best practices:

• Incremental Migration: Gradually migrate components, avoid rewriting everything at once.

• Testing: Robustly test components before and after migration to catch regressions.

• Performance Monitoring: Profile components to detect performance regressions.

• React's General Recommendations:

  • Keep components pure, side-effects should be managed explicitly.

  • Clearly define component boundaries and minimize component complexity.

  • Avoid unnecessary re-renders using techniques like memoization (React.memo, useMemo, useCallback).

🚫 Common Misconceptions and Myths

Avoid these common misunderstandings:

• "Hooks are just lifecycle methods with new syntax": They represent a different paradigm, focusing on state synchronization rather than lifecycle events.

• "Functional components are inherently faster": Performance depends on component logic, not the component type itself.

• "React skips rendering if props don’t change": React always calls render functions, though DOM updates occur only when changes happen.

🧭 What’s Next?

In future articles, we'll explore:

• Detailed internal workings of class components.

• Lifecycle method mappings.

• Functional component internals and migration tactics.

These articles will maintain a mentor-like mindset, prioritizing clarity, best practices, and quality.

🌟 Mentor’s Tip

React isn't just a UI library—it’s a mindset. Understanding React's core principles helps you write better, clearer, and more maintainable code. Invest in understanding first—your migration will thank you.

Happy learning!

Additional Resources:

• React Documentation - Components and Props

• React Docs – Render and Commit

• React Docs – Component Lifecycle Methods

• React Docs – useEffect

• React Fiber Architecture (by Andrew Clark)

• Overreacted – Dan Abramov’s Blog

• Mark Erikson – Guide to React Rendering Behavior

• Kent C. Dodds – Articles on Mental Models

This is the third article from the Unclass team, written with a strong sense of mentorship and care. In our last post, we discussed whether switching from class-based to functional components in React is the right choice. If you're here, you've likely decided that the migration is worthwhile. That's an important and thoughtful decision.

However, just like a craftsman doesn't start cutting wood without a plan, your next question should be: how will we do this correctly?

In this article, we’ll guide you in making two key decisions: choosing the right migration model and selecting an agile methodology that suits your team and situation. These choices can save you months of headaches—or cause them if made too quickly.

🧩 Assessing Your Starting Point

Before jumping into strategies, take a pause and reflect with your team:

• How many developers are available?

• What’s their seniority and experience with modern React?

• What’s the deadline or delivery window?

• How complex, coupled, or brittle is the current codebase?

This isn’t busywork. This is architectural awareness. Your answers will shape everything that follows.

🏗️ Choosing Your Migration Model

Let’s break down your options with honesty and care:

🔧 Refactoring

• When to use it: The codebase works reasonably well, and your goal is maintainability—not rebuilding.

• Approach: Gradually convert class components to functions during regular development. Think like a gardener pruning overgrown branches while keeping the tree alive.

• Ideal for: Teams that are actively shipping features, working in a stable environment, or don’t have the capacity for a full rewrite.

• Bonus: Emphasizes craftsmanship—“leave the code better than you found it.”

"Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior." — Martin Fowler

🧱 Rebuilding

This is when you need a fresh start, but it comes with significant trade-offs.

✳ By Blocks (Modular Rewrite)

• Migrate component groups or feature domains gradually.

• Maintain bridges between legacy and new parts.

• Allows for testing each new part in isolation.

🆕 From Scratch (Greenfield)

• Start a brand-new project with modern principles.

• Useful when the legacy system is too broken to salvage.

• Risky: Total rewrites often lead to underestimated timelines and forgotten edge cases.

"The big rewrite is one of the most dangerous moves in software. You're throwing away known behavior in exchange for hope." — Joel Spolsky

🧭 Selecting Your Agile Methodology

Migrations don't happen on their own. They need rhythm, structure, and routines. Let's discuss methodologies that help organize teams, not just track tickets.

We'll focus on team-level frameworks that shape how people collaborate—not just visual tools like Kanban, which can be added to any of these frameworks.

🌀 Extreme Programming (XP)

• Best for: Small, senior teams working under high urgency or with high standards.

• Core Values: Communication, simplicity, feedback, courage, respect.

• Practices: Test-driven development (TDD), pair programming, continuous integration, shared code ownership.

• Why it fits: Encourages small, safe iterations with constant validation. Perfect for refactoring or modular rebuilds.

"XP is about delivering value quickly and consistently, while keeping the code clean and sustainable." — Kent Beck

🧱 Feature-Driven Development (FDD)

• Best for: Large teams with clear business requirements and long-term roadmaps.

• Phases: Develop overall model → Build feature list → Plan by feature → Design by feature → Build by feature.

• Why it fits: Breaks the project into business-focused slices, which works well when rebuilding by domain.

• Limitation: Assumes that features are well-defined upfront—less flexible to changing requirements.

🍃 Lean Software Development

• Best for: Teams looking to minimize waste and focus on continuous improvement.

• Principles: Eliminate waste, amplify learning, defer commitment, deliver fast, build integrity in, empower the team, see the whole.

• Why it fits: Keeps your migration lightweight, deliberate, and focused on long-term outcomes.

🔮 Crystal

• Best for: Small teams that value flexibility over process.

• Philosophy: The team adapts the methodology to their needs, not the other way around.

• Why it fits: Migration projects often evolve—Crystal gives room for teams to tailor their pace and practices.

"Crystal is based on the recognition that every project is different and the people involved are the most important factor." — Alistair Cockburn

✅ Summary

Once you know you need to migrate, take a breath. Don’t just run to the code. Instead, create a plan that respects your people, your timeline, and the code’s complexity.

• Refactor if you can evolve your system steadily.

• Rebuild if the old system is beyond saving—but rebuild wisely.

• Choose XP if your team is senior and tight-knit.

• Choose FDD or Lean if you need structured deliverables.

• Use Crystal if you need freedom to adapt.

Whatever you choose, remember: you are not just migrating code—you’re guiding a team through change.

"The code we write is a reflection of our values. Migration is a chance to reaffirm them." — Unclass Team

In the next article, we’ll explore practical migration rhythms and edge-case patterns you can use once you’ve picked a direction.

Stay tuned—and refactor responsibly. 🚀

📚 References

🔄 Refactoring in Software Development

• Refactoring.Guru

• Martin Fowler

• IBM: What is Code Refactoring?

• SonarSource: Refactoring Guide

• Source Making

🏗️ Rebuilding (By Blocks and From Scratch)

• NetApp: Cloud Migration Approaches

• Intercept: App and Platform Modernization

• Coherent Solutions: Cloud Migration Strategy Guide

📈 Choosing the Right Agile Methodology

• Zenhub: Agile Frameworks Comparison

• AgileSherpas: Selecting the Right Agile Framework

• Cprime: Considerations for Choosing an Agile Framework

🌀 Extreme Programming (XP)

• GeeksforGeeks: Extreme Programming Overview

• Asana: Extreme Programming Guide

• Wikipedia: Extreme Programming

🧩 Feature-Driven Development (FDD)

• ProductPlan: Feature-Driven Development Explained

• Planview: FDD in Agile

• Wikipedia: Feature-Driven Development

🧠 Lean Software Development

• Planview: Lean Development Principles

• Wikipedia: Lean Software Development

• Atlassian: Lean Principles in DevOps

💎 Crystal Methodology

• ProductPlan: Crystal Agile Framework

• GeeksforGeeks: Crystal Methods in Agile

• Wrike: Crystal Agile Methodology Guide

This article is written as a letter from one software craftsman to another. Let it guide your path, save you from avoidable mistakes, and remind you that migrations—done right—are not burdens, but opportunities to rebuild trust, quality, and joy in your code.

This is the second article in the React migration series by the Unclass team. In the first article, we introduced the goals of this series and outlined the Unclass project. This time, we're stepping back to ask a more fundamental question: should you even migrate your class components at all?

Functional components with hooks have become the standard in the React ecosystem — but that doesn’t mean every team should jump in. We've gathered recent, engineering-focused insights and best practices to help you make a thoughtful, balanced decision.

Whether you're working with a legacy codebase or just exploring modern best practices, this article offers both sides of the conversation — so you can move forward with clarity and confidence.

👉 You’ll find all the references from our research at the end of this article.

✅ Why Teams Consider Migrating to Functional Components (Hooks)

🔧 Unlock Modern React Features

Functional components unlock the full power of React Hooks — like useState, useEffect, and custom hooks — that class components can't natively access. Today, most modern libraries in the React ecosystem offer hook-first APIs, making class components feel increasingly out of sync.

In short, moving to functions aligns your codebase with where React is headed.

⚡ Performance and Efficiency

Functional components are leaner by default — there's no this, less boilerplate, and fewer built-in assumptions. Some teams have reported up to a 30% reduction in bundle size and faster initial loads after switching to functional patterns.

Hooks like useEffect, useCallback, and useMemo let developers fine-tune performance, avoid unnecessary re-renders, and boost runtime speed — all while keeping the code clean and declarative.

🧼 Maintainability and Code Reuse

Hooks make it easier to write small, focused components. Instead of duplicating logic across class files, teams can extract and share behavior using custom hooks, supporting DRY and clean code principles.

This shift leads to a clearer separation of concerns and avoids the pain of bloated class components with 500+ lines of lifecycle logic. According to one survey, 75% of engineers say hooks reduce complexity and make code easier to maintain.
📚 Source: MoldStud

🧪 Improved Testability

Functional components are just plain JavaScript functions — easier to mock, test, and reason about. There’s no this, no constructor bindings, and no awkward lifecycle simulation in tests.

Custom hooks can be tested in isolation, reinforcing a software craftsmanship mindset focused on simplicity, verifiability, and confidence in your codebase.

🌍 Ecosystem and Community Standards

React’s docs, examples, tools, and third-party libraries are now overwhelmingly focused on functional components with hooks. Core features like concurrent rendering and Server Components are designed with functions in mind.

Migrating helps future-proof your app and ensures you're not working against the grain of where React — and the community — is heading.

👨‍💻 Developer Experience and Team Efficiency

Modern React developers often learn hooks first. Many teams report that junior devs or new hires are more comfortable working in functional style and struggle with older class patterns.

By unifying on one style, you reduce mental overhead, simplify onboarding, and make your codebase more approachable. No more wondering why this is undefined or which lifecycle method does what — just clean, functional logic.

🚫 Clear Reasons Not to Migrate (Yet)

🧘‍♂️ “If It Ain’t Broke, Don’t Fix It” (YAGNI)

The YAGNI principle — “You Aren’t Gonna Need It” — reminds us not to do unnecessary work.

If your class components are well-tested and your app isn’t lacking features that hooks solve, migrating just for trendiness can be wasteful. As one engineer put it:

“If there’s a new feature that benefits from hooks, migrate. Otherwise, why touch it?”

Every migration has cost and risk. Don’t fix what isn’t broken.

🏗️ Large Legacy Codebases and Consistency

Rewriting hundreds of components can introduce regressions and confusion. Especially in mature codebases, mixing styles (half class, half functional) without a clear plan can do more harm than good.

If your system is stable, consider maintaining consistency until there’s a strong need to modernize — or until it can be done incrementally with discipline.

⏳ Limited Time or Budget

Not every team has time to dedicate to technical refactors. If your roadmap is full of customer-facing features, a migration might feel like a luxury you can’t afford.

In this case, adopt the “Boy Scout Rule”: refactor only the components you touch for new features. Over time, the codebase will modernize itself — without slowing you down today.

📚 Team Familiarity

If your team is confident with class components but unfamiliar with hooks, a migration may slow you down. React still supports class components, and there's no plan to deprecate them.

Unless your team is ready to adopt the functional style fully, forcing a switch can introduce more bugs and confusion than it resolves.

🧩 Dependency or API Constraints

Some features — like Error Boundaries — still require class components (as of 2025). You may also rely on third-party libraries that assume class patterns.

In these rare cases, mixed paradigms are fine. Just verify that critical functionality or tooling won’t break before migrating.

✅ Conclusion: Migrate for Value, Not for Trend

React has clearly moved toward functional components, but your team’s migration decision should be based on value — not fashion.

✅ Migrate when it helps you:

• Leverage hooks

• Improve maintainability

• Reduce technical debt

• Align with modern tooling and hiring

❌ Delay migration when:

• Your app is stable and well-tested

• You lack time, budget, or need

• The risk outweighs the benefit

Craftsmanship means respecting context and solving real problems. Migrate when it makes your system more sustainable, testable, and productive — not because Twitter said so.

As always — write less code, make it better.

📚 References

• Ihnatovich, Dzmitry. From Class Components to Hooks: A Migration Strategy. Medium, 2025.

• Ifeanyi Emmanuel. Choosing Between Class and Functional Components in React. Stackademic, 2023.

• MoldStud (Cătălina Mărcuță et al.). Migrating from Class Components to Hooks – Effective State Management in React for MERN Apps. 2025.

• Glinteco. Why You Should Use Functional Components & Hooks in ReactJS. 2023.

• Reddit r/reactjs: “Is it a good decision to convert class-based components to functional components?” 2021.

• Stack Overflow: “Should we change class component to functional component?” Answer by rockTheWorld. 2020.

• Sean LaFlam. Is There Any Reason to Still Use React Class Components? Medium, 2021.

• Reddit r/reactnative: “Is it worth converting class-based components to functional components?” 2021.

• GeeksforGeeks. What is YAGNI principle (You Aren’t Gonna Need It)? 2024

Hi there! 👋
I'm Daniel, and together with my friend Alberto, we’re the team behind a project called Unclass.

We’ve been working in React for years — and we’ve experienced the frustration firsthand:
migrating from class components to function components isn’t just tedious... it can be a complete nightmare.

If you've ever dealt with this, binding event handlers, or digging through outdated lifecycle methods, you know what we mean.

💡 Why we’re building Unclass

Unclass is a CLI tool designed to help you automate the process of migrating your React class components into modern, functional ones — using hooks, clean syntax, and up-to-date best practices.

But here’s the thing: before we offer you automation, we want to do something different.

We want to show you everything that goes into this migration — manually, step by step, from scratch.
Because we believe the best tools don’t just work — they make you smarter and more confident about what’s happening under the hood.

That’s why we’re launching this blog series.

🔍 What you’ll learn in this series

Each week, I’ll publish a new article walking you through:

✅ The real reasons to migrate (and when you shouldn’t)
✅ How class components work internally
✅ How functional components work with hooks
✅ Manual migration steps — useState, useEffect, useRef, useContext, and more
✅ Advanced edge cases and how to handle them
✅ Tools and strategies to support large-scale migrations
✅ Behind the scenes of how Unclass works and why we designed it that way

By the end of the series, you'll be able to migrate components manually with confidence — and you’ll be ready to decide when to let a tool like Unclass take over.

🚀 Try the Free Analyzer

As part of our open approach, we will also build a free online analyzer that lets you inspect any class component and see what it would take to migrate it.

You’ll get:

• A breakdown of what your component uses (state, lifecycle, refs, etc.)

• A list of hooks you'd need to use

• A summary of migration complexity

• No code changes, just visibility and insight

👉 This tool will be available soon — and totally free.

🧭 What is Unclass, really?

Unclass is a CLI tool built with TypeScript, Project Builder, and Schematics under the hood. It works in three stages:

1. Analyze: Scan your component and understand what’s going on

2. Migrate: Generate a side-by-side functional version

3. Apply: Replace the original when you’re ready — safely

You get control, visibility, and speed — without breaking your code.

And we’re building it with care, transparency, and real-world developer pain in mind.

📬 Join Us on This Journey

If you’re currently working with legacy class components — or if you’re part of a team thinking about upgrading — this series is for you.

We’d love for you to:

• Follow the blog to get weekly insights

• Try the analyzer once it’s live

• Join the waitlist to be part of the first group to try Unclass CLI

• Help shape the tool by sharing your challenges and needs

Let’s make React migration less painful, and a lot more empowering.

Thanks for being here 🙌
— Daniel & Alberto