Simple Example React Code used on jsComplete.com

counter_reactjs.html

class Button extends React.Component {
  handleClick = () => {
		this.props.onClickFunction(this.props.incrementValue);
  };

	render() {
  	return (
    	<button onClick={this.handleClick}>
      	+{this.props.incrementValue}
      </button>
    );
  }
};

const Result = (props) => {
	return (
  	<div>{props.counter}</div>
    );
};


class App extends React.Component{
	state ={counter: 0}
  
  incrementCounter = (incrementValue) => {
    this.setState((prevState) => ({
        counter: prevState.counter + incrementValue
      }));
  };
  
	render() {
  	return (
    	<div>
      	<Button incrementValue={1} onClickFunction={this.incrementCounter} />
      	<Button incrementValue={5} onClickFunction={this.incrementCounter} />
      	<Button incrementValue={10} onClickFunction={this.incrementCounter} />
      	<Button incrementValue={100} onClickFunction={this.incrementCounter} />
        <Result counter={this.state.counter} />
      </div>
	    );
  }
}


ReactDOM.render(<App />, mountNode);

Thank you found this very helpful (the pluralsight video)