> ## Documentation Index > Fetch the complete documentation index at: https://mintlify.com/millionco/react-doctor/llms.txt > Use this file to discover all available pages before exploring further. # Rules Reference > Complete reference of all React Doctor linting rules organized by category React Doctor includes **60+ specialized rules** across 10 categories to catch React performance issues, architectural problems, and framework-specific bugs. ## Rule Categories 9 rules for proper state management and effect usage 10 rules for React rendering and animation performance 4 rules for component structure and code organization 6 rules for reducing JavaScript bundle size 2 rules for preventing security vulnerabilities 3 rules for common React mistakes and bugs 15 rules from jsx-a11y for accessible UIs 16 Next.js-specific optimization and correctness rules 8 React Native and Expo best practices Unused files, exports, types via Knip integration ## All Rules by Category ### State and Effects (9 rules) | Rule | Severity | Description | | ------------------------------------------- | -------- | -------------------------------------------------------- | | `react-doctor/no-derived-state-effect` | error | Detects state derived from props in useEffect | | `react-doctor/no-fetch-in-effect` | error | Prevents fetch() inside useEffect | | `react-doctor/no-cascading-set-state` | warn | Flags 3+ setState calls in one effect | | `react-doctor/no-effect-event-handler` | warn | Detects useEffect simulating event handlers | | `react-doctor/no-derived-useState` | warn | Catches useState initialized from props | | `react-doctor/prefer-useReducer` | warn | Suggests useReducer for 5+ related useState calls | | `react-doctor/rerender-lazy-state-init` | warn | Enforces lazy initialization for expensive computations | | `react-doctor/rerender-functional-setstate` | warn | Requires functional updates to avoid stale closures | | `react-doctor/rerender-dependencies` | error | Catches new object/array references in dependency arrays | ### Performance (10 rules) | Rule | Severity | Description | | ----------------------------------------------- | -------- | ------------------------------------------------------- | | `react-doctor/no-inline-prop-on-memo-component` | warn | Prevents inline props breaking memo() | | `react-doctor/no-usememo-simple-expression` | warn | Flags useMemo wrapping trivial expressions | | `react-doctor/no-layout-property-animation` | error | Prevents animating layout-triggering properties | | `react-doctor/no-transition-all` | warn | Flags transition: "all" for performance | | `react-doctor/no-global-css-variable-animation` | error | Prevents animating global CSS variables | | `react-doctor/no-large-animated-blur` | warn | Warns on expensive blur() animations | | `react-doctor/no-scale-from-zero` | warn | Suggests better scale animations | | `react-doctor/no-permanent-will-change` | warn | Detects permanent will-change declarations | | `react-doctor/rerender-memo-with-default-value` | warn | Catches {} and \[] default props on memoized components | | `react-doctor/rendering-hydration-no-flicker` | warn | Prevents mount-time setState causing flicker | ### Architecture (4 rules) | Rule | Severity | Description | | --------------------------------------------- | -------- | -------------------------------------------------- | | `react-doctor/no-generic-handler-names` | warn | Requires descriptive event handler names | | `react-doctor/no-giant-component` | warn | Flags components over 300 lines | | `react-doctor/no-render-in-render` | warn | Prevents inline render function calls | | `react-doctor/no-nested-component-definition` | error | Detects components defined inside other components | ### Bundle Size (6 rules) | Rule | Severity | Description | | ---------------------------------------- | -------- | --------------------------------------------- | | `react-doctor/no-barrel-import` | warn | Suggests direct imports over barrel files | | `react-doctor/no-full-lodash-import` | warn | Requires importing specific lodash functions | | `react-doctor/no-moment` | warn | Suggests date-fns or dayjs instead of moment | | `react-doctor/prefer-dynamic-import` | warn | Recommends code splitting for heavy libraries | | `react-doctor/use-lazy-motion` | warn | Enforces LazyMotion for framer-motion | | `react-doctor/no-undeferred-third-party` | warn | Requires defer/async on third-party scripts | ### Security (2 rules) | Rule | Severity | Description | | ---------------------------------------- | -------- | ------------------------------------------ | | `react-doctor/no-eval` | error | Prevents eval() and dynamic code execution | | `react-doctor/no-secrets-in-client-code` | error | Detects hardcoded secrets and API keys | ### Correctness (3 rules) | Rule | Severity | Description | | ------------------------------------------- | -------- | ------------------------------------------ | | `react-doctor/no-array-index-as-key` | warn | Prevents using array index as key prop | | `react-doctor/no-prevent-default` | warn | Suggests semantic HTML over preventDefault | | `react-doctor/rendering-conditional-render` | warn | Catches .length in conditional rendering | ### Accessibility (15 rules) All jsx-a11y rules from the oxlint plugin for accessible interfaces. ### Next.js (16 rules) Next.js-specific optimization and App Router best practices. ### React Native (8 rules) React Native and Expo platform-specific rules. ### Dead Code (4 categories) Knip integration for detecting unused files, exports, types, and duplicates. ## Rule Severity Levels * **error**: Must be fixed, indicates a bug or serious issue * **warn**: Should be reviewed, indicates a performance or maintainability concern ## Related * [Configuration Guide](/usage/configuration) - Learn how to customize which rules run * [CLI Commands](/usage/cli-commands) - How to use command line options