Since React 16.3 the way to add refs is to use React.createRef as Jeff Bowen pointed in his answer. However you can take advantage of Typescript to better type your ref.
In your example you're using ref on input element. So they way I would do it is:
class SomeComponent extends React.Component<IProps, IState> {
private inputRef: React.RefObject<HTMLInputElement>;
constructor() {
...
this.inputRef = React.createRef();
}
...
render() {
<input type="text" ref={this.inputRef} />;
}
}
By doing this when you want to make use of that ref you have access to all input methods:
someMethod() {
this.inputRef.current.focus(); // 'current' is input node, autocompletion, yay!
}
You can use it on custom components as well:
private componentRef: React.RefObject<React.Component<IProps>>;
and then have, for example, access to props :
this.componentRef.current.props; // 'props' satisfy IProps interface