web-development

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---
name: web-development
description: Web development context skill for React, Next.js, Vue, and Svelte projects. Covers component patterns, state management, performance optimization, API integration, and modern frontend/backend practices.
---

# Web Development

Context skill for modern web application development covering frontend patterns, backend integration, and full-stack best practices.

## Component Patterns

### Composition Over Inheritance

```typescript
interface CardProps {
  children: React.ReactNode
  variant?: 'default' | 'outlined'
}

export function Card({ children, variant = 'default' }: CardProps) {
  return <div className={`card card-${variant}`}>{children}</div>
}

export function CardHeader({ children }: { children: React.ReactNode }) {
  return <div className="card-header">{children}</div>
}

export function CardBody({ children }: { children: React.ReactNode }) {
  return <div className="card-body">{children}</div>
}
```

### Compound Components

```typescript
const TabsContext = createContext<{
  activeTab: string
  setActiveTab: (tab: string) => void
} | undefined>(undefined)

export function Tabs({ children, defaultTab }: {
  children: React.ReactNode
  defaultTab: string
}) {
  const [activeTab, setActiveTab] = useState(defaultTab)
  return (
    <TabsContext.Provider value={{ activeTab, setActiveTab }}>
      {children}
    </TabsContext.Provider>
  )
}
```

### Typed Functional Components

```typescript
interface ButtonProps {
  children: React.ReactNode
  onClick: () => void
  disabled?: boolean
  variant?: 'primary' | 'secondary'
}

export function Button({
  children,
  onClick,
  disabled = false,
  variant = 'primary'
}: ButtonProps) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      className={`btn btn-${variant}`}
    >
      {children}
    </button>
  )
}
```

## Custom Hooks

### Debounce Hook

```typescript
export function useDebounce<T>(value: T, delay: number): T {
  const [debouncedValue, setDebouncedValue] = useState<T>(value)

  useEffect(() => {
    const handler = setTimeout(() => setDebouncedValue(value), delay)
    return () => clearTimeout(handler)
  }, [value, delay])

  return debouncedValue
}
```

### Data Fetching Hook

```typescript
export function useQuery<T>(
  key: string,
  fetcher: () => Promise<T>,
  options?: { enabled?: boolean }
) {
  const [data, setData] = useState<T | null>(null)
  const [error, setError] = useState<Error | null>(null)
  const [loading, setLoading] = useState(false)

  const refetch = useCallback(async () => {
    setLoading(true)
    setError(null)
    try {
      const result = await fetcher()
      setData(result)
    } catch (err) {
      setError(err as Error)
    } finally {
      setLoading(false)
    }
  }, [fetcher])

  useEffect(() => {
    if (options?.enabled !== false) refetch()
  }, [key, refetch, options?.enabled])

  return { data, error, loading, refetch }
}
```

### Toggle Hook

```typescript
export function useToggle(initial = false): [boolean, () => void] {
  const [value, setValue] = useState(initial)
  const toggle = useCallback(() => setValue(v => !v), [])
  return [value, toggle]
}
```

## State Management

### Context + Reducer

```typescript
type Action =
  | { type: 'SET_ITEMS'; payload: Item[] }
  | { type: 'SET_LOADING'; payload: boolean }

function reducer(state: State, action: Action): State {
  switch (action.type) {
    case 'SET_ITEMS':
      return { ...state, items: action.payload }
    case 'SET_LOADING':
      return { ...state, loading: action.payload }
    default:
      return state
  }
}
```

### Immutable State Updates

```typescript
// Always spread, never mutate
const updated = { ...user, name: 'New Name' }
const withNewItem = [...items, newItem]
const withoutItem = items.filter(i => i.id !== removeId)
```

## Performance Optimization

### Memoization

```typescript
const sorted = useMemo(() =>
  items.sort((a, b) => b.value - a.value),
  [items]
)

const handleSearch =