name: refactoring_patterns
router_kit: FullStackKit
description: Common refactoring patterns - Extract, Rename, Move and code smell solutions.
metadata:
skillport:
category: quality
tags: [architecture, automation, best practices, clean code, coding, collaboration, compliance, debugging, design patterns, development, documentation, efficiency, git, optimization, productivity, programming, project management, quality assurance, refactoring, refactoring patterns, software engineering, standards, testing, utilities, version control, workflow] - refactoring-strategies

🔄 Refactoring Patterns

Common refactoring patterns and code smell solutions.

🎯 Golden Rule

Do NOT change behavior, only improve structure

Before: Input X → [Code A] → Output Y
After:  Input X → [Code B] → Output Y (SAME!)

🔍 Code Smells

📦 Extract Method

// ❌ Before
function processOrder(order) {
  // 20 lines of validation
  // 30 lines of calculation
  // 15 lines of formatting
}

// ✅ After
function processOrder(order) {
  validateOrder(order);
  const total = calculateTotal(order);
  return formatOutput(total);
}

🔄 Replace Conditional with Polymorphism

// ❌ Before
function getPrice(type) {
  if (type === 'premium') return 100;
  if (type === 'basic') return 50;
  return 30;
}

// ✅ After
const pricing = { premium: 100, basic: 50, free: 30 };
const getPrice = (type) => pricing[type] ?? 30;

Refactoring Patterns v1.1 - Enhanced

🔄 Workflow

Source: Refactoring.guru & Martin Fowler - Refactoring

Phase 1: Preparation (Safety First)

• [ ] Red-Green-Refactor: Do you have tests? If not, write tests first ("Characterization Tests"), then refactor.
• [ ] Small Steps: Make changes in atomic commits. Run tests after every step.
• [ ] Backup: Work on a clean branch in VCS (Git).

Phase 2: Applying Patterns

• [ ] Simplification: Simplify complex conditions with Decompose Conditional or Replace Nested Conditional with Guard Clauses.
• [ ] Abstraction: Separate responsibilities (SRP) with Extract Method and Extract Class. If there is Primitive Obsession, convert to Value Object.
• [ ] Modernization: Apply var -> const/let, for -> map/filter, Callback -> Async/Await conversions (Use language features).

Phase 3: Verification & Cleanup

• [ ] Regression Testing: Verify that existing functions are not broken.
• [ ] Dead Code: Delete unused code (Dead Code) ruthlessly. Do not comment it out, delete it (It's already in Git history).
• [ ] Naming: Update variable and function names to describe "why" the code does what it does, not just what it does.

Checkpoints