状態を URL と同期するためのカスタム React フック

npm install react-router-dom

import { useCallback, useState } from 'react';
import { useSearchParams } from 'react-router-dom';

/**
 * A custom hook that syncs state with a URL search parameter.
 * Supports string, number, boolean, and object values.
 * @param key The search parameter key to sync with.
 * @param defaultValue The default value for the state.
 * @returns A stateful value, and a function to update it.
 */
function useParamState<T extends string | number | boolean | object>(
  key: string,
  defaultValue: T
): [T, (newValue: Partial<T> | T) => void] {
  const [searchParams, setSearchParams] = useSearchParams();
  const paramValue = searchParams.get(key);

  const [state, setState] = useState<T>(() => {
    if (paramValue === null) {
      return defaultValue;
    }
    try {
      return JSON.parse(paramValue) as T;
    } catch {
      return paramValue as T;
    }
  });

  const setParamState = useCallback(
    (newValue: Partial<T> | T) => {
      const updatedValue = typeof newValue === 'object' && !Array.isArray(newValue)
        ? { ...state, ...newValue }
        : newValue;

      setState(updatedValue as T);
      const newSearchParams = new URLSearchParams(searchParams);
      newSearchParams.set(key, JSON.stringify(updatedValue));
      setSearchParams(newSearchParams);
    },
    [key, searchParams, setSearchParams, state]
  );

  return [state, setParamState];
}

export default useParamState;

import React from 'react';
import useParamState from './useParamState';

interface FilterState {
  status: string;
  sortBy: string;
}

const MyComponent: React.FC = () => {
  const [filter, setFilter] = useParamState<FilterState>('filter', {
    status: 'all',
    sortBy: 'date',
  });

  return (
    <div>
      <h2>Current Filter: {filter.status}, Sort by: {filter.sortBy}</h2>
      <button onClick={() => setFilter({ status: 'active', sortBy: filter.sortBy })}>
        Active
      </button>
      <button onClick={() => setFilter({ status: 'completed', sortBy: filter.sortBy })}>
        Completed
      </button>
      <button onClick={() => setFilter({ ...filter, sortBy: 'priority' })}>
        Sort by Priority
      </button>
    </div>
  );
};

export default MyComponent;

import { renderHook, act } from '@testing-library/react';
import { MemoryRouter } from 'react-router-dom';
import useParamState from './useParamState';

interface FilterState {
  status: string;
  sortBy: string;
}

test('should sync object state with search params', () => {
  const wrapper = ({ children }: { children: React.ReactNode }) => (
    <MemoryRouter initialEntries={['/']}>{children}</MemoryRouter>
  );

  const { result } = renderHook(() => useParamState<FilterState>('filter', { status: 'all', sortBy: 'date' }), { wrapper });

  // Initial state
  expect(result.current[0]).toEqual({ status: 'all', sortBy: 'date' });

  // Update state and URL
  act(() => {
    result.current[1]({ status: 'active', sortBy: 'priority' });
  });

  // Updated state
  expect(result.current[0]).toEqual({ status: 'active', sortBy: 'priority' });
});