JSX元素类型'App'不是JSX元素的构造函数.属性'setState'的类型是不兼容的

Question

我正在使用Microsoft TypeScript-React-Starter并在以下期间遇到此编译错误npm start:

./src/index.tsx
(16,5): error TS2605: JSX element type 'App' is not a constructor function for JSX elements.
  Types of property 'setState' are incompatible.
    Type '{ <K extends never>(f: (prevState: null, props: {}) => Pick<null, K>, callback?: (() => any) | un...' is not assignable to type '{ <K extends never>(f: (prevState: {}, props: any) => Pick<{}, K>, callback?: (() => any) | undef...'.
      Types of parameters 'f' and 'f' are incompatible.
        Type '(prevState: {}, props: any) => Pick<{}, any>' is not assignable to type '(prevState: null, props: {}) => Pick<null, any>'.
          Types of parameters 'prevState' and 'prevState' are incompatible.
            Type 'null' is not assignable to type '{}'.

所以看起来我的setState功能有不正确的签名,但我不知道如何解决它.这是我的代码:

class App extends React.Component<{}, null> {
  render() {
    return (
      <div className="App">
        ...
      </div>
    );
  }
}

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root') as HTMLElement
);

我在用:

node v6.11.0
npm v5.1.0
typescript v2.4.1
react v15.6.1
redux v3.7.1
react-redux v5.0.5
react-scripts-ts v2.3.2

更新:

我发现删除泛型类型可以<{}, null>清除错误.但我仍然想知道为什么我会收到错误.

Answer 1

TLDR; 国家不能为空.为它声明一个接口或声明它{}

答案在于@ types/react

查看定义,state和props都不是null.

当你声明App为class App extends React.Component<{}, null> {,你基本上说,"状态是null类型".

现在,类型setState取决于您为state指定的类型,并且它与setState api的较小的已知版本冲突.prevState声明为{}(默认情况下,因为没有指定state的接口),这与null不兼容,导致您看到的错误日志.