actions建议封装起来，方便后续的维护和扩展（下面是伪代码）

// actions.js
const deepCopy = obj => JSON.parse(JSON.stringify(obj))
const actions = {
	//...
	change_input_value(state, action){
		const newState = deepCopy(state)
		newState.inputValue = action.value
		return newState
	}
	//...
	add_todo_item(state){
		const newState = deepCopy(state)
		newState.list.push(newState.inputValue)
		newState.inputValue = ''
		return newState
	}
}

export default actions

// store.js
import actions from './actions'
export default function(state, action){
	const type = action.type
	if(actions[type] && typeof actions[type] === 'function'){
		return actions[type](state, action)
	}
}

到后期项目做大了，还可以对 actions 进行拆分：

// login.actions.js
export default {
	signup(state,action){}
	signin(state,actions){}
}

// order.actions.js
export default {
	getOrderList(state,action){}
	getOrderDetail(state,action){}
}

在 actions 中统一导出，这样在团队分工的时候，可以A负责一个模块，B负责另外一个模块，代码也不容易冲突

// actions.js
import loginActions from './login.actions'
import orderActions from './order.actions'
const actions = {
	...loginActions,
	...orderActions
}
export default actions