react-refactoring

React Component Refactoring Skill

This skill provides a systematic approach to refactoring complex React components. The goal is to transform monolithic, tangled code into clean, modular, and maintainable structures, specifically targeting code length and structure issues.

When to Use

Trigger this skill when you encounter:

1. Excessive Length: File size exceeds 200-300 lines.
2. Tangled Logic: Business logic, API calls, and state management are mixed directly with UI rendering.
3. Complex State: Multiple useState or useEffect calls make the flow hard to follow.
4. Deep Nesting: Render methods contain deeply nested conditionals or loops.
5. Cognitive Overload: The component is difficult to read or understand quickly.

Core Principles

1. Single Responsibility: Each component or hook should do one thing well.
2. Separation of Concerns: Strictly separate View (JSX/UI) from Logic (State/Effects/Handlers).
3. Composition: Build complex interfaces by composing smaller, focused sub-components.
4. Colocation: Keep related styles, types, and helpers close to where they are used.

Refactoring Workflow

Follow these steps to safely refactor functionality without breaking it.

Step 1: Analyze & Audit

Before making changes, map out the component:

• Identify State: usage of useState, useReducer.
• Identify Effects: usage of useEffect, external API calls.
• Identify UI Sections: Logically distinct parts of the render (e.g., Header, FilterBar, List, Modal).

Step 2: Extract Logic (Custom Hooks)

Move logic out of the component to reduce lines of code and clarify intent.

Goal: The main component should mostly contain purely presentational logic and simple event handlers.

Pattern:

// ❌ BEFORE: Monolithic
const Dashboard = () => {
  const [data, setData] = useState([]);
  const [loading, setLoading] = useState(true);
  useEffect(() => { /* fetch logic */ }, []);
  const handleSort = () => { /* sort logic */ };
  
  return <div>...</div>
}

// ✅ AFTER: Separated Logic
// hooks/useDashboardLogic.ts
export const useDashboardLogic = () => {
  const [data, setData] = useState([]);
  const [loading, setLoading] = useState(true);
  useEffect(() => { /* fetch logic */ }, []);
  const handleSort = () => { /* sort logic */ };
  
  return { data, loading, handleSort };
}

// Dashboard.tsx
const Dashboard = () => {
  const { data, loading, handleSort } = useDashboardLogic();
  return <div>...</div>
}

Step 3: Decompose the UI

Break the return (...) JSX into smaller, named components.

Goal: The main component's render method should read like a table of contents.

Strategy:

1. Identify a distinct section of JSX (e.g., a list item or a header).
2. Extract it to a local variable or function first to verify isolation.
3. Move it to a separate named component (e.g., DashboardHeader, ProjectList).

Pattern:

// ❌ BEFORE: Deeply nested JSX
return (
  <div className="container">
     <div className="header">
        <h1>Title</h1>
        <button onClick={...}>Add</button>
     </div>
     <ul>
       {items.map(item => (
         <li key={item.id}>
            <span>{item.name}</span>
            {/* ... complex item logic ... */}
         </li>
       ))}
     </ul>
  </div>
)

// ✅ AFTER: Composed Components
return (
  <div className="container">
    <DashboardHeader onAdd={handleAdd} />
    <ProjectList items={items} />
  </div>
)

Step 4: Organize Files

If the component is large enough to split into multiple files, create a dedicated directory.

Recommended Structure:

/app/dashboard/plan/
  ├── page.tsx            # Main container (View + Hook integration)
  ├── hooks/
  │   └── usePlanLogic.ts # Business logic
  ├── components/
  │   ├── PlanHeader.tsx  # Sub-component
  │   ├── PlanList.tsx    # Sub-component
  │   └── types.ts        # Local types

Refactoring Checklist

• Type Safety: Prop interfaces are defined for all new sub-components.
• Naming: Component and Hook names are descriptive (useProjectData vs useData).
• Simplicity: No component exceeds 150 lines after refactoring.
• Maintainability: Magic numbers/strings are extracted to constants.

Example: Refactoring PlannerPage

If refactoring a complex page like PlannerPage:

1. Extract Data: Move task fetching, Drag-and-Drop sensors, and optimistic updates to hooks/usePlanner.ts.
2. Split UI:
   • PlannerToolbar: Search, filters, view toggles.
   • PlannerBoard: The main grid/list.
   • TaskItem: Individual task rendering.
3. Result: page.tsx becomes a clean coordinator of these parts.