react-sample-1

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={3} onClickFunction={this.incrementCounter}/>
        <Button incrementValue={4} onClickFunction={this.incrementCounter}/>
        <Button incrementValue={25} onClickFunction={this.incrementCounter}/>
        <Button incrementValue={100} onClickFunction={this.incrementCounter}/>
        <Result counter={this.state.counter} />
    	</div>
    )
  }
}

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