# Typescript Refactor

> Safely refactor TypeScript code while maintaining type safety and test coverage. Includes verification steps.

- Skill: `majiayu000/typescript-refactor` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/typescript-refactor`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/typescript-refactor/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/typescript-refactor

---


# TypeScript Refactor Skill

Safely refactor TypeScript code with full verification.

## Pre-Refactor Checklist

1. Run current tests to establish baseline:

   ```bash
   npm run test
   ```

2. Run type check:

   ```bash
   npm run typecheck
   ```

3. Note current state as baseline

## Refactoring Patterns

### Extract Function

```typescript
// Before
function process(data: Data) {
  // complex validation logic
  if (!data.field1) throw new Error("field1 required");
  if (!data.field2) throw new Error("field2 required");
  // ... more processing
}

// After
function validateData(data: Data): void {
  if (!data.field1) throw new Error("field1 required");
  if (!data.field2) throw new Error("field2 required");
}

function process(data: Data) {
  validateData(data);
  // ... more processing
}
```

### Extract Component (React)

```typescript
// Before: Large component with repeated patterns
// After: Smaller, focused components with clear props
```

### Rename Symbol

```bash
# Find all usages first
grep -r "oldName" --include="*.ts" --include="*.tsx" src/
```

## Post-Refactor Verification

1. Run type check:

   ```bash
   npm run typecheck
   ```

2. Run tests:

   ```bash
   npm run test
   ```

3. Run linter:

   ```bash
   npm run lint
   ```

4. Build project:
   ```bash
   npm run build
   ```

## Rules

- Never change behavior during refactor
- One refactor type at a time
- Commit after each successful refactor
- If tests fail, rollback immediately