具有多种变化的传播属性：单线性ecma不变性

Question

我刚刚改变了这个

const newCities = {...newState.cities};
newCities[action.payload.id] = action.payload;
newState.cities = newCities;

到单行

newState.cities = {...newState.cities, [action.payload.id]: action.payload};

但我该如何更改

const newCities = {...newState.cities};
action.payload.forEach(city=> newCities[city.id] = city);
newState.cities = newCities;

到单线？东西〜=

newState.cities = {...newState.cities, action.payload.map(city=> [city.id]: city)};

Answer 1

最终解决方案：

News.category(params['categori']).tag(params['tag_list'])

以前我忘了初始化reduce array =）

旧方法： 可能是这样吗？

newState.cities = {...newState.cities, ...action.payload.reduce((o,a)=> ({...o,[a.id]:a}),{})};

<强>更新

newState.cities = {...newState.cities, ...action.payload.map(city=> ({[city.id]: city}) )};

更新（完整丑陋）：

newState.cities = {...newState.cities, ...action.payload.reduce(city=> ({[city.id]:city}) )};