Class Components

React.Component is used to describe a class component. React.Component is a generic type that takes two optional type variables, PropType and StateType.

The following example is from the react-typescript-cheatsheet.

type MyProps = {
  // using `interface` is also ok
  message: string;
};
type MyState = {
  count: number; // like this
};
class App extends React.Component<MyProps, MyState> {
  state: MyState = {
    // optional second annotation for better type inference
    count: 0,
  };
  render() {
    return (
      <div>
        {this.props.message} {this.state.count}
      </div>
    );
  }
}

This video explains another example of typing a class component.