useReducer钩子，如何检查动作的类型？

const ActionType = {
  INCREMENT: 'INCREMENT',
  DECREMENT: 'DECREMENT',
};

const reducer = (state, action) => {
  switch (action.type) {
    case ActionType.INCREMENT:
      return { count: state.count + 1 };
    case ActionType.DECREMENT:
      return { count: state.count - 1 };
    default:
      throw new Error(`Unsupported action type: ${action.type}`);
  }
};

import React, { useReducer } from 'react';

const initialState = { count: 0 };

const Counter = () => {
  const [state, dispatch] = useReducer(reducer, initialState);

  const handleIncrement = () => {
    dispatch({ type: ActionType.INCREMENT });
  };

  const handleDecrement = () => {
    dispatch({ type: ActionType.DECREMENT });
  };

  return (
    <div>
      <p>Count: {state.count}</p>
      <button onClick={handleIncrement}>Increment</button>
      <button onClick={handleDecrement}>Decrement</button>
    </div>
  );
};