???? ??? ???? ??? ?? ??? ????!

???? API? ???? ?? ? ?? ??? ?? ??? ?????.

? ?? ??? ??? ? ???? ?? ?? ????? ???? ??? ????.

? ?? ?? ? ?? ??? ?? ???? React Context API? ??? ?? ??? ? ????.

?? ???? ??

???? ???? ?? ?? "??"? ??? ???? ??? ?? ??? ? ????.

(??? ??? ??? ?? ?????.)

import {
  createContext,
  useCallback,
  useContext,
  useDeferredValue,
  useMemo,
  useState,
} from 'react';

function useContextValue(init: number = 0) {
  const [state, setState] = useState(init);

  const doubleValue = state * 2;
  const defferedStringValue = useDeferredValue(state.toString());

  const reset = useCallback(() => {
    setState(init);
  }, []);

  const value = useMemo(
    () => ({
      state,
      doubleValue,
      defferedStringValue,
      reset,
    }),
    [
      state,
      doubleValue,
      defferedStringValue,
      reset,
    ],
  );

  return value;
}

type ExampleContext = ReturnType<typeof useContextValue>;

const Context = createContext<ExampleContext>(null!);

Context.displayName = 'ExampleContext';

export function ExampleContextProvider({
  children,
  initValue = 0,
}: {
  children: React.ReactNode;
  initValue?: number;
}) {
  const value = useContextValue(initValue);
  return <Context.Provider value={value}>{children}</Context.Provider>;
}

export function useExample() {
  const value = useContext(Context);

  if (!value) {
    throw new Error('useExample must be used within a ExampleContextProvider');
  }

  return value;
}

??? ?? ??

import {
  createContext,
  useCallback,
  useContext,
  useDeferredValue,
  useMemo,
  useState,
} from 'react';

/**
 * We create a custom hook that will have everything
 * that would usually be in the context main function
 *
 * this way, we can use the value it returns to infer the
 * type of the context
 */
function useContextValue(init: number = 0) {
  // do whatever you want inside

  const [state, setState] = useState(init);

  const doubleValue = state * 2;
  const defferedStringValue = useDeferredValue(state.toString());

  // remember to memoize functions
  const reset = useCallback(() => {
    setState(init);
  }, []);

  // and also memoize the final value
  const value = useMemo(
    () => ({
      state,
      doubleValue,
      defferedStringValue,
      reset,
    }),
    [
      state,
      doubleValue,
      defferedStringValue,
      reset,
    ],
  );

  return value;
}

/**
 * Since we can infer from the hook,
 * no need to create the context type by hand
 */
type ExampleContext = ReturnType<typeof useContextValue>;

const Context = createContext<ExampleContext>(null!);

Context.displayName = 'ExampleContext';

export function ExampleContextProvider({
  children,
  /**
   * this is optional, but it's always a good to remember
   * that the context is still a react component
   * and can receive values other than just the children
   */
  initValue = 0,
}: {
  children: React.ReactNode;
  initValue?: number;
}) {
  const value = useContextValue(initValue);
  return <Context.Provider value={value}>{children}</Context.Provider>;
}

/**
 * We also export a hook that will use the context
 *
 * this way, we can use it in other components
 * by importing just this one hook
 */
export function useExample() {
  const value = useContext(Context);

  /**
   * this will throw an error if the context
   * is not used within the provider
   *
   * this also avoid the context being "undefined"
   */
  if (!value) {
    throw new Error('useExample must be used within a ExampleProvider');
  }

  return value;
}

?? ??

?????. Context API? ???? ?? ????? ???? ?? ???? ??? ?????.

React Context API? Redux(?? ?? ?? ???)? ??? ?? ?????? ??? ??? ???? ? ??? ?? ?????.

?????. ??? ???? ??? ??? ? ????.

? ?? React < 19? ??? ?? ??? ????? ???? ?? ? ???? ???? ??? ???? ?? ? ????.

? ??? ??? ????? ?? React Context API ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!