javascript - 这个 JavaScript 对象解构是如何工作的？

Question

我试图理解这个 React redux 示例:https://codesandbox.io/s/f2ded

在reducer.js中，初始状态是:

const initialState = {
  taskName: "",
  tasks: []
};

在App.js中，我们有:

const mapStateToProps = state => {
  return {
    ...state.list
  };
};

state 没有属性 list，并且 state.list 应该是一个空对象{}。但是，它实际上成立

感谢任何有助于理解其具体工作原理的帮助。谢谢。

Answer 1

这是因为底部的combineReducers

const reds = combineReducers({ list });

export default reds;

这意味着 Redux 状态的该部分中的所有内容都是 state.list.taskName 或 state.list.tasks 等。

[编辑]只是想从官方文档中添加一些清晰度，https://redux.js.org/api/combinereducers/

rootReducer = combineReducers({potato: potatoReducer, tomato: tomatoReducer})
// This would produce the following state object
{
  potato: {
    // ... potatoes, and other state managed by the potatoReducer ...
  },
  tomato: {
    // ... tomatoes, and other state managed by the tomatoReducer, maybe some nice sauce? ...
  }
}