TypeScript interface signature for the onClick event in ReactJS

Is there a way to replace the 'any' keyword in the IProps_Square interface with an explicit function signature

I would just () => void i.e. a function that takes no arguments and you don't care if it returns anything.

import * as React from 'react';   
import * as ReactDOM from 'react-dom'; 

interface IProps_Square {
  message: string,
  onClick: () => void,
}

class Square extends React.Component < IProps_Square > {
   render() {  
     return (
       <button onClick={this.props.onClick}>
         {this.props.message}
       </button>
     );
   }
}

class Game extends React.Component {
  render() {
    return (
      <Square
         message = { 'click this' }
         onClick = { () => alert('hello') }
      />
    );
  }
}

ReactDOM.render(
  <Game />, 
  document.getElementById('reactjs-tutorial')   
); 

However if you need the parameter the proper type for it is React.MouseEvent<HTMLElement>, so:

interface IProps_Square {
  message: string,
  onClick: (e: React.MouseEvent<HTMLElement>) => void,
}

The interface with props should be

interface IProps_Square {
  message: string;
  onClick: React.MouseEventHandler<HTMLButtonElement>;
}

Notice also that if you use semicolons, the interface items separator is a semicolon, not a comma.