- Reducer（处理动作）：
const reducer = (state = { age: 18 }, action) => {
if (action.type === 'ADD_AGE') {
return { ...state, age: state.age + action.payload };
}
return state;
};- （接收当前年龄和“加1”指令，返回新年龄）
const reducer = (state = { age: 18 }, action) => {
if (action.type === 'ADD_AGE') {
return { ...state, age: state.age + action.payload };
}
return state;
};