纯函数

数组

const state = []
save(state, { payload: todoList }) {
    return [...state, todoList];
}

const state = []
save(state, { payload: todoList }) {
    return state.concat(todoList);
}

对象

const state = {
    name: 'bob',
    age: 18
}
save(state, { payload: userInfo }) {
    return {
        ...state,
        ...userInfo
    }
}