Counter.jsx

import React, { useReducer } from 'react';

const initialState = { count: 0 };

function reducer(state, action) {
  switch (action.type) {
    case 'INCREMENT':
      return {count: state.count + 1};
    case 'DECREMENT':
      return {count: state.count - 1};
    default:
      return state;
  }
}

function Counter() {
  const [state, dispatch] = useReducer(reducer, initialState);
  return (
    <>
      Count: {state.count}
      <button onClick={() => dispatch({type: 'DECREMENT'})}>-</button>
      <button onClick={() => dispatch({type: 'INCREMENT'})}>+</button>
    </>
  );
}