react-class-to-functional

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Convert React class components to functional components with hooks

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React Class to Functional Component Converter

Convert the React class component at $ARGUMENTS to a functional component using React hooks.

Conversion Rules

State

this.state = { ... } → individual useState hooks
this.setState({ key: value }) → setter function
this.setState(prev => ...) → functional update form

Mutable objects (Set/Map) must be cloned on update:

setExpandedRows(prev => { const next = new Set(prev); next.add(key); return next; });

Lifecycle → useEffect

Class	Functional
`componentDidMount`	`useEffect(fn, [])`
`componentDidUpdate`	`useEffect(fn)` or `useEffect(fn, [deps])`
`componentWillUnmount`	`useEffect(() => cleanup, [])`
mount + unmount	single `useEffect` with cleanup return

Other Mappings

React.createRef() → useRef(null)
static contextType → useContext(MyContext)
Bound methods / arrow class methods → local function inside functional component
Non-reactive instance variables (this.timer) → useRef
createSelector (reselect) → useMemo with explicit dependency array

Props and Defaults

this.props.x → destructured props
static defaultProps → default parameter values

Critical: mark defaultProps as optional (?) in the interface:

interface Props { sortSetting?: SortSetting; }
function Component({ sortSetting = defaultValue }: Props) { ... }

setState with Callback

this.setState(update, callback) has no direct hook equivalent. Use ref + useEffect:

const pendingRef = useRef(false);
const prevRef = useRef(value);

const onUpdate = useCallback(() => {
  pendingRef.current = true;
  setValue(newValue);
}, []);

useEffect(() => {
  if (pendingRef.current && prevRef.current !== value) {
    pendingRef.current = false;
    doCallback();
  }
  prevRef.current = value;
}, [value, doCallback]);

Generic Components

class MyTable extends SortedTable<Row> {} → const MyTable = SortedTable<Row>;
Exported type aliases require the props interface to also be exported (else "cannot be named" build errors)
TypeScript may fail to infer generics with spread props — add explicit type params: <SortedTable<Row> {...props} />

Workflow

Read the file and summarize: state vars, lifecycle methods, refs, methods, generics, files extending this class
Before converting each method, verify it's actually called — delete dead code, don't convert it
Write the converted component, preserving imports/comments/exports and adding hook imports
Search for and update dependent files that extend the class