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frontend-patterns
Frontend development patterns for React, Next.js, state management, performance optimization, and UI best practices.
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Frontend development patterns for React, Next.js, state management, performance optimization, and UI best practices.
Track and report Claude Code token usage, spending, and budgets from the local ECC cost-tracker metrics log. Use when the user asks about costs, spending, usage, tokens, budgets, or cost breakdowns by model, session, or date.
Instinct-based learning system that observes sessions via hooks, creates atomic instincts with confidence scoring, and evolves them into skills/commands/agents. v2.1 adds project-scoped instincts to prevent cross-project contamination.
Create reproducible, cross-platform (macOS/Linux) development environments with Flox, a declarative Nix-based environment manager. Use when setting up project toolchains for any language, installing system-level dependencies (compilers, databases, native libs like openssl/BLAS), pinning exact package versions for a team, running local services (PostgreSQL, Redis, Kafka), onboarding developers with one command, or solving 'works on my machine' problems — including agent/vibe-coding setups that need project-scoped tools without sudo. Also use when the user mentions .flox/, manifest.toml, flox activate, or FloxHub.
Commercial-grade Python installer expert for Windows: Nuitka extreme compilation, dist slimming, DLL footprint analysis, and Inno Setup packaging to ship the smallest, fastest installers. Use only for advanced packaging/optimization (minimal size, fast startup), not basic script-to-exe conversion. 中文触发:Nuitka 极限优化、Python 商业打包、极限编译 Python、dist 瘦身、DLL 分析、最小安装包、最快启动、商业级打包风格
Use when a brand needs to discover or articulate its identity through structured multi-session interviews. Covers purpose, positioning, audience, personality, voice, narrative, and founder-brand tension across 8 modules using laddering, 5 Whys, and projective techniques. Produces a resumable session with disk-persisted state and a master brandbook (90_SYNTHESIS.md).
Use when a brand needs to discover or articulate its identity through structured multi-session interviews. Covers purpose, positioning, audience, personality, voice, narrative, and founder-brand tension across 8 modules using laddering, 5 Whys, and projective techniques. Produces a resumable session with disk-persisted state and a master brandbook (90_SYNTHESIS.md).
| name | frontend-patterns |
| description | Frontend development patterns for React, Next.js, state management, performance optimization, and UI best practices. |
用於 React、Next.js 和高效能使用者介面的現代前端模式。
// PASS: 良好:元件組合
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>
}
// 使用方式
<Card>
<CardHeader>標題</CardHeader>
<CardBody>內容</CardBody>
</Card>
interface TabsContextValue {
activeTab: string
setActiveTab: (tab: string) => void
}
const TabsContext = createContext<TabsContextValue | 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>
)
}
export function TabList({ children }: { children: React.ReactNode }) {
return <div className="tab-list">{children}</div>
}
export function Tab({ id, children }: { id: string, children: React.ReactNode }) {
const context = useContext(TabsContext)
if (!context) throw new Error('Tab must be used within Tabs')
return (
<button
className={context.activeTab === id ? 'active' : ''}
onClick={() => context.setActiveTab(id)}
>
{children}
</button>
)
}
// 使用方式
<Tabs defaultTab="overview">
<TabList>
<Tab id="overview">概覽</Tab>
<Tab id="details">詳情</Tab>
</TabList>
</Tabs>
interface DataLoaderProps<T> {
url: string
children: (data: T | null, loading: boolean, error: Error | null) => React.ReactNode
}
export function DataLoader<T>({ url, children }: DataLoaderProps<T>) {
const [data, setData] = useState<T | null>(null)
const [loading, setLoading] = useState(true)
const [error, setError] = useState<Error | null>(null)
useEffect(() => {
fetch(url)
.then(res => res.json())
.then(setData)
.catch(setError)
.finally(() => setLoading(false))
}, [url])
return <>{children(data, loading, error)}</>
}
// 使用方式
<DataLoader<Market[]> url="/api/markets">
{(markets, loading, error) => {
if (loading) return <Spinner />
if (error) return <Error error={error} />
return <MarketList markets={markets!} />
}}
</DataLoader>
export function useToggle(initialValue = false): [boolean, () => void] {
const [value, setValue] = useState(initialValue)
const toggle = useCallback(() => {
setValue(v => !v)
}, [])
return [value, toggle]
}
// 使用方式
const [isOpen, toggleOpen] = useToggle()
interface UseQueryOptions<T> {
onSuccess?: (data: T) => void
onError?: (error: Error) => void
enabled?: boolean
}
export function useQuery<T>(
key: string,
fetcher: () => Promise<T>,
options?: UseQueryOptions<T>
) {
const [data, setData] = useState<T | null>(null)
const [error, setError] = useState<Error | null>(null)
const [loading, setLoading] = useState(false)
// 將最新的 fetcher/options 保存在 ref 中,讓 refetch 即使在呼叫端
// 傳入行內函式與物件字面值時也能保持參照穩定。
// 若沒有這麼做,每次渲染都會建立新的 refetch,下方的 effect 會在
// 每次狀態更新後重新執行,造成無限取得迴圈。
const fetcherRef = useRef(fetcher)
const optionsRef = useRef(options)
useEffect(() => {
fetcherRef.current = fetcher
optionsRef.current = options
})
const refetch = useCallback(async () => {
setLoading(true)
setError(null)
try {
const result = await fetcherRef.current()
setData(result)
optionsRef.current?.onSuccess?.(result)
} catch (err) {
const error = err as Error
setError(error)
optionsRef.current?.onError?.(error)
} finally {
setLoading(false)
}
}, [])
const enabled = options?.enabled !== false
useEffect(() => {
if (enabled) {
refetch()
}
}, [key, enabled, refetch])
return { data, error, loading, refetch }
}
// 使用方式
const { data: markets, loading, error, refetch } = useQuery(
'markets',
() => fetch('/api/markets').then(r => r.json()),
{
onSuccess: data => console.log('Fetched', data.length, 'markets'),
onError: err => console.error('Failed:', err)
}
)
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
}
// 使用方式
const [searchQuery, setSearchQuery] = useState('')
const debouncedQuery = useDebounce(searchQuery, 500)
useEffect(() => {
if (debouncedQuery) {
performSearch(debouncedQuery)
}
}, [debouncedQuery])
interface State {
markets: Market[]
selectedMarket: Market | null
loading: boolean
}
type Action =
| { type: 'SET_MARKETS'; payload: Market[] }
| { type: 'SELECT_MARKET'; payload: Market }
| { type: 'SET_LOADING'; payload: boolean }
function reducer(state: State, action: Action): State {
switch (action.type) {
case 'SET_MARKETS':
return { ...state, markets: action.payload }
case 'SELECT_MARKET':
return { ...state, selectedMarket: action.payload }
case 'SET_LOADING':
return { ...state, loading: action.payload }
default:
return state
}
}
const MarketContext = createContext<{
state: State
dispatch: Dispatch<Action>
} | undefined>(undefined)
export function MarketProvider({ children }: { children: React.ReactNode }) {
const [state, dispatch] = useReducer(reducer, {
markets: [],
selectedMarket: null,
loading: false
})
return (
<MarketContext.Provider value={{ state, dispatch }}>
{children}
</MarketContext.Provider>
)
}
export function useMarkets() {
const context = useContext(MarketContext)
if (!context) throw new Error('useMarkets must be used within MarketProvider')
return context
}
// PASS: useMemo 用於昂貴計算
// 排序前先複製 - Array.prototype.sort 會就地修改陣列
const sortedMarkets = useMemo(() => {
return [...markets].sort((a, b) => b.volume - a.volume)
}, [markets])
// PASS: useCallback 用於傳遞給子元件的函式
const handleSearch = useCallback((query: string) => {
setSearchQuery(query)
}, [])
// PASS: React.memo 用於純元件
export const MarketCard = React.memo<MarketCardProps>(({ market }) => {
return (
<div className="market-card">
<h3>{market.name}</h3>
<p>{market.description}</p>
</div>
)
})
import { lazy, Suspense } from 'react'
// PASS: 延遲載入重型元件
const HeavyChart = lazy(() => import('./HeavyChart'))
const ThreeJsBackground = lazy(() => import('./ThreeJsBackground'))
export function Dashboard() {
return (
<div>
<Suspense fallback={<ChartSkeleton />}>
<HeavyChart data={data} />
</Suspense>
<Suspense fallback={null}>
<ThreeJsBackground />
</Suspense>
</div>
)
}
import { useVirtualizer } from '@tanstack/react-virtual'
export function VirtualMarketList({ markets }: { markets: Market[] }) {
const parentRef = useRef<HTMLDivElement>(null)
const virtualizer = useVirtualizer({
count: markets.length,
getScrollElement: () => parentRef.current,
estimateSize: () => 100, // 預估行高
overscan: 5 // 額外渲染的項目數
})
return (
<div ref={parentRef} style={{ height: '600px', overflow: 'auto' }}>
<div
style={{
height: `${virtualizer.getTotalSize()}px`,
position: 'relative'
}}
>
{virtualizer.getVirtualItems().map(virtualRow => (
<div
key={virtualRow.index}
style={{
position: 'absolute',
top: 0,
left: 0,
width: '100%',
height: `${virtualRow.size}px`,
transform: `translateY(${virtualRow.start}px)`
}}
>
<MarketCard market={markets[virtualRow.index]} />
</div>
))}
</div>
</div>
)
}
interface FormData {
name: string
description: string
endDate: string
}
interface FormErrors {
name?: string
description?: string
endDate?: string
}
export function CreateMarketForm() {
const [formData, setFormData] = useState<FormData>({
name: '',
description: '',
endDate: ''
})
const [errors, setErrors] = useState<FormErrors>({})
const validate = (): boolean => {
const newErrors: FormErrors = {}
if (!formData.name.trim()) {
newErrors.name = '名稱為必填'
} else if (formData.name.length > 200) {
newErrors.name = '名稱必須少於 200 個字元'
}
if (!formData.description.trim()) {
newErrors.description = '描述為必填'
}
if (!formData.endDate) {
newErrors.endDate = '結束日期為必填'
}
setErrors(newErrors)
return Object.keys(newErrors).length === 0
}
const handleSubmit = async (e: React.FormEvent) => {
e.preventDefault()
if (!validate()) return
try {
await createMarket(formData)
// 成功處理
} catch (error) {
// 錯誤處理
}
}
return (
<form onSubmit={handleSubmit}>
<input
value={formData.name}
onChange={e => setFormData(prev => ({ ...prev, name: e.target.value }))}
placeholder="市場名稱"
/>
{errors.name && <span className="error">{errors.name}</span>}
{/* 其他欄位 */}
<button type="submit">建立市場</button>
</form>
)
}
interface ErrorBoundaryState {
hasError: boolean
error: Error | null
}
export class ErrorBoundary extends React.Component<
{ children: React.ReactNode },
ErrorBoundaryState
> {
state: ErrorBoundaryState = {
hasError: false,
error: null
}
static getDerivedStateFromError(error: Error): ErrorBoundaryState {
return { hasError: true, error }
}
componentDidCatch(error: Error, errorInfo: React.ErrorInfo) {
console.error('Error boundary caught:', error, errorInfo)
}
render() {
if (this.state.hasError) {
return (
<div className="error-fallback">
<h2>發生錯誤</h2>
<p>{this.state.error?.message}</p>
<button onClick={() => this.setState({ hasError: false })}>
重試
</button>
</div>
)
}
return this.props.children
}
}
// 使用方式
<ErrorBoundary>
<App />
</ErrorBoundary>
import { motion, AnimatePresence } from 'framer-motion'
// PASS: 列表動畫
export function AnimatedMarketList({ markets }: { markets: Market[] }) {
return (
<AnimatePresence>
{markets.map(market => (
<motion.div
key={market.id}
initial={{ opacity: 0, y: 20 }}
animate={{ opacity: 1, y: 0 }}
exit={{ opacity: 0, y: -20 }}
transition={{ duration: 0.3 }}
>
<MarketCard market={market} />
</motion.div>
))}
</AnimatePresence>
)
}
// PASS: Modal 動畫
export function Modal({ isOpen, onClose, children }: ModalProps) {
return (
<AnimatePresence>
{isOpen && (
<>
<motion.div
className="modal-overlay"
initial={{ opacity: 0 }}
animate={{ opacity: 1 }}
exit={{ opacity: 0 }}
onClick={onClose}
/>
<motion.div
className="modal-content"
initial={{ opacity: 0, scale: 0.9, y: 20 }}
animate={{ opacity: 1, scale: 1, y: 0 }}
exit={{ opacity: 0, scale: 0.9, y: 20 }}
>
{children}
</motion.div>
</>
)}
</AnimatePresence>
)
}
export function Dropdown({ options, onSelect }: DropdownProps) {
const [isOpen, setIsOpen] = useState(false)
const [activeIndex, setActiveIndex] = useState(0)
const handleKeyDown = (e: React.KeyboardEvent) => {
switch (e.key) {
case 'ArrowDown':
e.preventDefault()
setActiveIndex(i => Math.min(i + 1, options.length - 1))
break
case 'ArrowUp':
e.preventDefault()
setActiveIndex(i => Math.max(i - 1, 0))
break
case 'Enter':
e.preventDefault()
onSelect(options[activeIndex])
setIsOpen(false)
break
case 'Escape':
setIsOpen(false)
break
}
}
return (
<div
role="combobox"
aria-expanded={isOpen}
aria-haspopup="listbox"
onKeyDown={handleKeyDown}
>
{/* 下拉選單實作 */}
</div>
)
}
export function Modal({ isOpen, onClose, children }: ModalProps) {
const modalRef = useRef<HTMLDivElement>(null)
const previousFocusRef = useRef<HTMLElement | null>(null)
useEffect(() => {
if (isOpen) {
// 儲存目前聚焦的元素
previousFocusRef.current = document.activeElement as HTMLElement
// 聚焦 modal
modalRef.current?.focus()
} else {
// 關閉時恢復焦點
previousFocusRef.current?.focus()
}
}, [isOpen])
return isOpen ? (
<div
ref={modalRef}
role="dialog"
aria-modal="true"
tabIndex={-1}
onKeyDown={e => e.key === 'Escape' && onClose()}
>
{children}
</div>
) : null
}
記住:現代前端模式能實現可維護、高效能的使用者介面。選擇符合你專案複雜度的模式。