button.jsx

import React from 'react';

class Button extends React.Component {
    clicked() {
        this.props.onClicked(this.props.increment);
    }

    render() {
        return (
            <div>
            <button onClick={() => this.clicked()}>+{this.props.increment}</button>
            </div>
        );
    }
}

export default Button;

index.jsx

import React from 'react';
import {render} from 'react-dom';
import Button from './Button.jsx';
import Result from './Result.jsx';

class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = {likesCount: 0};
    }

    onLike(increment) {
        let newLikesCount = this.state.likesCount + increment;
        this.setState({likesCount: newLikesCount});
    }

    render() {
        return (
            <div>
                <p>Hello From React!</p>   
                <Button onClicked={() => this.onLike()} increment={1} />
                <Button onClicked={() => this.onLike()} increment={5} />
                <Button onClicked={() => this.onLike()} increment={10} />
                <Button onClicked={() => this.onLike()} increment={100} />
                <Result count={this.state.likesCount}/>
            </div>
        );
    }
}

render(<App />, document.getElementById('app'));

Result.jsx

import React from 'react';

class Result extends React.Component {
    render() {
        return (
            <div>{this.props.count}</div>
        );
    }
}

export default Result;