affaan-m
Frontend development patterns for React, Next.js, state management, performance optimization, and UI best practices.
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用於 React、Next.js 和高效能使用者介面的現代前端模式。
// ✅ 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)
const refetch = useCallback(async () => {
setLoading(true)
setError(null)
try {
const result = await fetcher()
setData(result)
options?.onSuccess?.(result)
} catch (err) {
const error = err as Error
setError(error)
options?.onError?.(error)
} finally {
setLoading(false)
}
}, [fetcher, options])
useEffect(() => {
if (options?.enabled !== false) {
refetch()
}
}, [key, refetch, options?.enabled])
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
}
// ✅ useMemo 用於昂貴計算
const sortedMarkets = useMemo(() => {
return markets.sort((a, b) => b.volume - a.volume)
}, [markets])
// ✅ useCallback 用於傳遞給子元件的函式
const handleSearch = useCallback((query: string) => {
setSearchQuery(query)
}, [])
// ✅ 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'
// ✅ 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'
// ✅ 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>
)
}
// ✅ 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。
Use when you need to run Flow type checking, or when seeing Flow type errors in React code.
Use when you want to validate changes before committing, or when you need to check all React contribution requirements.
Use when feature flag tests fail, flags need updating, understanding @gate pragmas, debugging channel-specific test failures, or adding new flags to React.
Use when you need to check feature flag states, compare channels, or debug why a feature behaves differently across release channels.