元素描述符的.kind属性必须为“方法”或“字段”

Question

我正在关注文档，mobx-react-router但是尝试运行我的应用程序时，在浏览器中出现以下错误：

Uncaught TypeError: An element descriptor's .kind property must be either "method" or "field", but a decorator created an element descriptor with .kind "undefined"
    at _toElementDescriptor (app.js:49988)
    at _toElementFinisherExtras (app.js:49990)
    at _decorateElement (app.js:49980)
    at app.js:49976
    at Array.forEach (<anonymous>)
    at _decorateClass (app.js:49976)
    at _decorate (app.js:49958)
    at Module../src/App/UserStore.js (app.js:50012)
    at __webpack_require__ (bootstrap:19)
    at Module../src/index.js (index.js:1)

这是我初始化的方式：

const appContainer = document.getElementById('app');
if(appContainer) {
  const browserHistory = createBrowserHistory()
  const routingStore = new RouterStore();

  const stores = {
    users: userStore,
    routing: routingStore
  }

  const history = syncHistoryWithStore(browserHistory, routingStore);

  ReactDOM.render(
    (
      <Provider {...stores}>
        <Router history={history}>
          < App />
        </Router>
      </Provider>
    ),
  appContainer);
}

这就是我的用法：

@inject('routing')
@inject('users')
@observer
class App extends Component { ...

我的UserStore：

import { observable, action, computed } from "mobx"

class UserStore {
  @observable users = [];

  @action addUser = (user) => {
    this.users.push(user)
  }

  @computed get userCount () {
    return this.users.length
  }
}

const store = new UserStore();
export default store;

我曾尝试向Google发送此错误，但未返回任何有用的结果。有什么想法我做错了吗？

Answer 1

如果您使用的是Babel 7，则对装饰器安装支持：

npm i -D\
  @babel/plugin-proposal-class-properties\
  @babel/plugin-proposal-decorators

然后在您的.babelrc或webpack.config.js文件中启用它：

{
    "plugins": [
        ["@babel/plugin-proposal-decorators", { "legacy": true}],
        ["@babel/plugin-proposal-class-properties", { "loose": true}]
    ]
}

请注意，传统模式很重要（将装饰器提案放在首位）。非旧版模式是WIP。

参考：https : //mobx.js.org/best/decorators.html