No,Category,Guideline,Description,Do,Don't,Code Good,Code Bad,Severity,Docs URL
1,State,Use useState for local state,Simple component state should use useState hook,useState for form inputs toggles counters,Class components this.state,"const [count, setCount] = useState(0)",this.state = { count: 0 },Medium,https://react.dev/reference/react/useState
2,State,Lift state up when needed,Share state between siblings by lifting to parent,Lift shared state to common ancestor,Prop drilling through many levels,Parent holds state passes down,Deep prop chains,Medium,https://react.dev/learn/sharing-state-between-components
3,State,Use useReducer for complex state,Complex state logic benefits from reducer pattern,useReducer for state with multiple sub-values,Multiple useState for related values,useReducer with action types,5+ useState calls that update together,Medium,https://react.dev/reference/react/useReducer
4,State,Avoid unnecessary state,Derive values from existing state when possible,Compute derived values in render,Store derivable values in state,const total = items.reduce(...),"const [total, setTotal] = useState(0)",High,https://react.dev/learn/choosing-the-state-structure
5,State,Initialize state lazily,Use function form for expensive initial state,useState(() => computeExpensive()),useState(computeExpensive()),useState(() => JSON.parse(data)),useState(JSON.parse(data)),Medium,https://react.dev/reference/react/useState#avoiding-recreating-the-initial-state
6,Effects,Clean up effects,Return cleanup function for subscriptions timers,Return cleanup function in useEffect,No cleanup for subscriptions,useEffect(() => { sub(); return unsub; }),useEffect(() => { subscribe(); }),High,https://react.dev/reference/react/useEffect#connecting-to-an-external-system
7,Effects,Specify dependencies correctly,Include all values used inside effect in deps array,All referenced values in dependency array,Empty deps with external references,[value] when using value in effect,[] when using props/state in effect,High,https://react.dev/reference/react/useEffect#specifying-reactive-dependencies
8,Effects,Avoid unnecessary effects,Don't use effects for transforming data or events,Transform data during render handle events directly,useEffect for derived state or event handling,const filtered = items.filter(...),useEffect(() => setFiltered(items.filter(...))),High,https://react.dev/learn/you-might-not-need-an-effect
9,Effects,Use refs for non-reactive values,Store values that don't trigger re-renders in refs,useRef for interval IDs DOM elements,useState for values that don't need render,const intervalRef = useRef(null),"const [intervalId, setIntervalId] = useState()",Medium,https://react.dev/reference/react/useRef
10,Rendering,Use keys properly,Stable unique keys for list items,Use stable IDs as keys,Array index as key for dynamic lists,key={item.id},key={index},High,https://react.dev/learn/rendering-lists#keeping-list-items-in-order-with-key
11,Rendering,Memoize expensive calculations,Use useMemo for costly computations,useMemo for expensive filtering/sorting,Recalculate every render,"useMemo(() => expensive(), [deps])",const result = expensiveCalc(),Medium,https://react.dev/reference/react/useMemo
12,Rendering,Memoize callbacks passed to children,Use useCallback for functions passed as props,useCallback for handlers passed to memoized children,New function reference every render,"useCallback(() => {}, [deps])",const handler = () => {},Medium,https://react.dev/reference/react/useCallback
13,Rendering,Use React.memo wisely,Wrap components that render often with same props,memo for pure components with stable props,memo everything or nothing,memo(ExpensiveList),memo(SimpleButton),Low,https://react.dev/reference/react/memo
14,Rendering,Avoid inline object/array creation in JSX,Create objects outside render or memoize,Define style objects outside component,Inline objects in props,<div style={styles.container}>,<div style={{ margin: 10 }}>,Medium,
15,Components,Keep components small and focused,Single responsibility for each component,One concern per component,Large multi-purpose components,<UserAvatar /><UserName />,<UserCard /> with 500 lines,Medium,
16,Components,Use composition over inheritance,Compose components using children and props,Use children prop for flexibility,Inheritance hierarchies,<Card>{content}</Card>,class SpecialCard extends Card,Medium,https://react.dev/learn/thinking-in-react
17,Components,Colocate related code,Keep related components and hooks together,Related files in same directory,Flat structure with many files,components/User/UserCard.tsx,components/UserCard.tsx + hooks/useUser.ts,Low,
18,Components,Use fragments to avoid extra DOM,Fragment or <> for multiple elements without wrapper,<> for grouping without DOM node,Extra div wrappers,<>{items.map(...)}</>,<div>{items.map(...)}</div>,Low,https://react.dev/reference/react/Fragment
19,Props,Destructure props,Destructure props for cleaner component code,Destructure in function signature,props.name props.value throughout,"function User({ name, age })",function User(props),Low,
20,Props,Provide default props values,Use default parameters or defaultProps,Default values in destructuring,Undefined checks throughout,function Button({ size = 'md' }),if (size === undefined) size = 'md',Low,
21,Props,Avoid prop drilling,Use context or composition for deeply nested data,Context for global data composition for UI,Passing props through 5+ levels,<UserContext.Provider>,<A user={u}><B user={u}><C user={u}>,Medium,https://react.dev/learn/passing-data-deeply-with-context
22,Props,Validate props with TypeScript,Use TypeScript interfaces for prop types,interface Props { name: string },PropTypes or no validation,interface ButtonProps { onClick: () => void },Button.propTypes = {},Medium,
23,Events,Use synthetic events correctly,React normalizes events across browsers,e.preventDefault() e.stopPropagation(),Access native event unnecessarily,onClick={(e) => e.preventDefault()},onClick={(e) => e.nativeEvent.preventDefault()},Low,https://react.dev/reference/react-dom/components/common#react-event-object
24,Events,Avoid binding in render,Use arrow functions in class or hooks,Arrow functions in functional components,bind in render or constructor,const handleClick = () => {},this.handleClick.bind(this),Medium,
25,Events,Pass event handlers not call results,Pass function reference not invocation,onClick={handleClick},onClick={handleClick()} causing immediate call,onClick={handleClick},onClick={handleClick()},High,
26,Forms,Controlled components for forms,Use state to control form inputs,value + onChange for inputs,Uncontrolled inputs with refs,<input value={val} onChange={setVal}>,<input ref={inputRef}>,Medium,https://react.dev/reference/react-dom/components/input#controlling-an-input-with-a-state-variable
27,Forms,Handle form submission properly,Prevent default and handle in submit handler,onSubmit with preventDefault,onClick on submit button only,<form onSubmit={handleSubmit}>,<button onClick={handleSubmit}>,Medium,
28,Forms,Debounce rapid input changes,Debounce search/filter inputs,useDeferredValue or debounce for search,Filter on every keystroke,useDeferredValue(searchTerm),useEffect filtering on every change,Medium,https://react.dev/reference/react/useDeferredValue
29,Hooks,Follow rules of hooks,Only call hooks at top level and in React functions,Hooks at component top level,Hooks in conditions loops or callbacks,"const [x, setX] = useState()","if (cond) { const [x, setX] = useState() }",High,https://react.dev/reference/rules/rules-of-hooks
30,Hooks,Custom hooks for reusable logic,Extract shared stateful logic to custom hooks,useCustomHook for reusable patterns,Duplicate hook logic across components,const { data } = useFetch(url),Duplicate useEffect/useState in components,Medium,https://react.dev/learn/reusing-logic-with-custom-hooks
31,Hooks,Name custom hooks with use prefix,Custom hooks must start with use,useFetch useForm useAuth,fetchData or getData for hook,function useFetch(url),function fetchData(url),High,
32,Context,Use context for global data,Context for theme auth locale,Context for app-wide state,Context for frequently changing data,<ThemeContext.Provider>,Context for form field values,Medium,https://react.dev/learn/passing-data-deeply-with-context
33,Context,Split contexts by concern,Separate contexts for different domains,ThemeContext + AuthContext,One giant AppContext,<ThemeProvider><AuthProvider>,<AppProvider value={{theme user...}}>,Medium,
34,Context,Memoize context values,Prevent unnecessary re-renders with useMemo,useMemo for context value object,New object reference every render,"value={useMemo(() => ({...}), [])}","value={{ user, theme }}",High,
35,Performance,Use React DevTools Profiler,Profile to identify performance bottlenecks,Profile before optimizing,Optimize without measuring,React DevTools Profiler,Guessing at bottlenecks,Medium,https://react.dev/learn/react-developer-tools
36,Performance,Lazy load components,Use React.lazy for code splitting,lazy() for routes and heavy components,Import everything upfront,const Page = lazy(() => import('./Page')),import Page from './Page',Medium,https://react.dev/reference/react/lazy
37,Performance,Virtualize long lists,Use windowing for lists over 100 items,react-window or react-virtual,Render thousands of DOM nodes,<VirtualizedList items={items}/>,{items.map(i => <Item />)},High,
38,Performance,Batch state updates,React 18 auto-batches but be aware,Let React batch related updates,Manual batching with flushSync,setA(1); setB(2); // batched,flushSync(() => setA(1)),Low,https://react.dev/learn/queueing-a-series-of-state-updates
39,ErrorHandling,Use error boundaries,Catch JavaScript errors in component tree,ErrorBoundary wrapping sections,Let errors crash entire app,<ErrorBoundary><App/></ErrorBoundary>,No error handling,High,https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary
40,ErrorHandling,Handle async errors,Catch errors in async operations,try/catch in async handlers,Unhandled promise rejections,try { await fetch() } catch(e) {},await fetch() // no catch,High,
41,Testing,Test behavior not implementation,Test what user sees and does,Test renders and interactions,Test internal state or methods,expect(screen.getByText('Hello')),expect(component.state.name),Medium,https://testing-library.com/docs/react-testing-library/intro/
42,Testing,Use testing-library queries,Use accessible queries,getByRole getByLabelText,getByTestId for everything,getByRole('button'),getByTestId('submit-btn'),Medium,https://testing-library.com/docs/queries/about#priority
43,Accessibility,Use semantic HTML,Proper HTML elements for their purpose,button for clicks nav for navigation,div with onClick for buttons,<button onClick={...}>,<div onClick={...}>,High,https://react.dev/reference/react-dom/components#all-html-components
44,Accessibility,Manage focus properly,Handle focus for modals dialogs,Focus trap in modals return focus on close,No focus management,useEffect to focus input,Modal without focus trap,High,
45,Accessibility,Announce dynamic content,Use ARIA live regions for updates,aria-live for dynamic updates,Silent updates to screen readers,"<div aria-live=""polite"">{msg}</div>",<div>{msg}</div>,Medium,
46,Accessibility,Label form controls,Associate labels with inputs,htmlFor matching input id,Placeholder as only label,"<label htmlFor=""email"">Email</label>","<input placeholder=""Email""/>",High,
47,TypeScript,Type component props,Define interfaces for all props,interface Props with all prop types,any or missing types,interface Props { name: string },function Component(props: any),High,
48,TypeScript,Type state properly,Provide types for useState,useState<Type>() for complex state,Inferred any types,useState<User | null>(null),useState(null),Medium,
49,TypeScript,Type event handlers,Use React event types,React.ChangeEvent<HTMLInputElement>,Generic Event type,onChange: React.ChangeEvent<HTMLInputElement>,onChange: Event,Medium,
50,TypeScript,Use generics for reusable components,Generic components for flexible typing,Generic props for list components,Union types for flexibility,<List<T> items={T[]}>,<List items={any[]}>,Medium,
51,Patterns,Container/Presentational split,Separate data logic from UI,Container fetches presentational renders,Mixed data and UI in one,<UserContainer><UserView/></UserContainer>,<User /> with fetch and render,Low,
52,Patterns,Render props for flexibility,Share code via render prop pattern,Render prop for customizable rendering,Duplicate logic across components,<DataFetcher render={data => ...}/>,Copy paste fetch logic,Low,https://react.dev/reference/react/cloneElement#passing-data-with-a-render-prop
53,Patterns,Compound components,Related components sharing state,Tab + TabPanel sharing context,Prop drilling between related,<Tabs><Tab/><TabPanel/></Tabs>,<Tabs tabs={[]} panels={[...]}/>,Low,
