React.js 5

<script type="text/babel">
        (() =>{

            function Counter(props){

            function countUp(){
                alert('count up!');
            }
            return(
                <li style={{backgroundColor:props.color}} onClick={countUp}>
                0
                </li>
            );
        }

            ReactDOM.render(
                <div className="container">
                    <ul>
                        <Counter color="red"/>
                        <Counter color="yellow"/>
                        <Counter color="blue"/>
                    </ul>
                </div>,
                document.getElementById('root')
            );
    })();
    </script>

function Counter(props){

            function countUp(color){
                alert(color);
            }
            return(
                <li style={{backgroundColor:props.color}} onClick={() =>
                    countUp(props.color)}>
                0
                </li>
            );
        }

<script type="text/babel">
        (() =>{


            class Counter extends React.Component {
                render(){
                    return(
                        <li style={{backgroundColor:this.props.color}}>
                            0
                        </li>
                    );
            }
        }

            ReactDOM.render(
                <div className="container">
                    <ul>
                        <Counter color="red"/>
                        <Counter color="yellow"/>
                        <Counter color="blue"/>
                    </ul>
                </div>,
                document.getElementById('root')
            );
    })();
    </script>

<script type="text/babel">
        (() =>{


            class Counter extends React.Component {
                constructor(props){
                super(props);
                this.state = {
                    count: 10
            };
            }

                render(){
                    return(
                        <li style={{backgroundColor:this.props.color}}>
                            {this.state.count}
                        </li>
                    );
            }
        }

            ReactDOM.render(
                <div className="container">
                    <ul>
                        <Counter color="red"/>
                        <Counter color="yellow"/>
                        <Counter color="blue"/>
                    </ul>
                </div>,
                document.getElementById('root')
            );
    })();
    </script>

class Counter extends React.Component {
                constructor(props){
                super(props);
                this.state = {
                    count: 10,
                    message: 'hello!'
            };
            }

<script type="text/babel">
        (() =>{


            class Counter extends React.Component {
                constructor(props){
                super(props);
                this.state = {
                    count: 0
                };
                this.countUp = this.countUp.bind(this);
            }
                countUp(){
                    this.setState(prevState =>{
                        return {
                        count: prevState.count + 1
                    };
                });
            }

                render(){
                    return(
                        <li style={{backgroundColor:this.props.color}} onClick={this.countUp}>
                            {this.state.count}
                        </li>
                    );
            }
        }

            ReactDOM.render(
                <div className="container">
                    <ul>
                        <Counter color="red"/>
                        <Counter color="yellow"/>
                        <Counter color="blue"/>
                    </ul>
                </div>,
                document.getElementById('root')
            );
    })();
    </script>

<script type="text/babel">
        (() =>{


            function Counter(props){
            return(
                        <li style={{backgroundColor:props.counter.color}}>
                            {props.counter.id}:{props.counter.count}
                        </li>
                );

            }

            class App extends React.Component {
                constructor(){
                    super();
                    this.state = {
                    counters: [
                        {id: 'A', count: 0, color: 'red'},
                        {id: 'B', count: 0, color: 'yellow'},
                        {id: 'C', count: 0, color: 'blue'}
                    ]

                };
            }
                render(){
                return (
                    <div className="container">
                        <ul>
                            <Counter counter={this.state.counters&#91;0&#93;}/>
                            <Counter counter={this.state.counters&#91;1&#93;}/>
                            <Counter counter={this.state.counters&#91;2&#93;}/>
                        </ul>
                        <div>Total Inventory: 3</div>
                    </div>
                )
            }
        }

            ReactDOM.render(
                <App/>,
                document.getElementById('root')
            );
    })();
    </script>

<script type="text/babel">
        (() =>{


            function Counter(props){
            return(
                        <li style={{backgroundColor:props.counter.color}}>
                            {props.counter.id}:{props.counter.count}
                        </li>
                );

            }

            function CounterList(props){
                const counters = props.counters.map(counter => {
                    return(
                        <Counter counter={counter}/>
                    );
            });
                return (
                    <ul>
                        {counters}
                    </ul>
                );
        }

            class App extends React.Component {
                constructor(){
                    super();
                    this.state = {
                    counters: [
                        {id: 'A', count: 0, color: 'red'},
                        {id: 'B', count: 0, color: 'yellow'},
                        {id: 'C', count: 0, color: 'blue'}
                    ]

                };
            }
                render(){
                return (
                    <div className="container">
                         <CounterList counters={this.state.counters}/>
                        <div>Total Inventory: 3</div>
                    </div>
                )
            }
        }

            ReactDOM.render(
                <App/>,
                document.getElementById('root')
            );
    })();
    </script>

function CounterList(props){
                const counters = props.counters.map(counter => {
                    return(
                        <Counter
                        counter={counter}
                        key={counter.id}/>
                    );
            });

<script type="text/babel">
        (() =>{


            function Counter(props){
            return(
                        <li style={{backgroundColor:props.counter.color}} onClick={() => props.countUp(props.counter)}>
                            {props.counter.id}:{props.counter.count}
                        </li>
                );

            }

            function CounterList(props){
                const counters = props.counters.map(counter => {
                    return(
                        <Counter
                        counter={counter}
                        key={counter.id}
                        countUp={props.countUp}
                        />
                    );
            });
                return (
                    <ul>
                        {counters}
                    </ul>
                );
        }

            class App extends React.Component {
                constructor(){
                    super();
                    this.state = {
                    counters: [
                        {id: 'A', count: 0, color: 'red'},
                        {id: 'B', count: 0, color: 'yellow'},
                        {id: 'C', count: 0, color: 'blue'}
                    ]

                };
                this.countUp = this.countUp.bind(this);
            }

            countUp(counter){
                this.setState(prevState =>{
                    const counters = prevState.counters.map(counter => {
                    return {id: counter.id, count: counter.count, color: counter.color};
                });
                const pos = counters.map(counter => {
                    return counter.id;
            }). indexOf(counter.id);
                counters[pos].count++;
                return {
                counters: counters
            };
            });
        }
                render(){
                return (
                    <div className="container">
                         <CounterList
                         counters={this.state.counters}
                            countUp={this.countUp}
                         />
                        <div>Total Inventory: 3</div>
                    </div>
                )
            }
        }

            ReactDOM.render(
                <App/>,
                document.getElementById('root')
            );
    })();
    </script>

<script type="text/babel">
        (() =>{


            function Counter(props){
            return(
                        <li style={{backgroundColor:props.counter.color}} onClick={() => props.countUp(props.counter)}>
                            {props.counter.id}:{props.counter.count}
                        </li>
                );

            }

            function CounterList(props){
                const counters = props.counters.map(counter => {
                    return(
                        <Counter
                        counter={counter}
                        key={counter.id}
                        countUp={props.countUp}
                        />
                    );
            });
                return (
                    <ul>
                        {counters}
                    </ul>
                );
        }

            class App extends React.Component {
                constructor(){
                    super();
                    this.state = {
                    counters: [
                        {id: 'A', count: 0, color: 'red'},
                        {id: 'B', count: 0, color: 'yellow'},
                        {id: 'C', count: 0, color: 'blue'}
                    ],
                    total: 0

                };
                this.countUp = this.countUp.bind(this);
            }

            countUp(counter){
                this.setState(prevState =>{
                    const counters = prevState.counters.map(counter => {
                    return {id: counter.id, count: counter.count, color: counter.color};
                });
                const pos = counters.map(counter => {
                    return counter.id;
            }). indexOf(counter.id);
                counters[pos].count++;
                return {
                counters: counters,
                total: prevState.total + 1
            };
            });
        }
                render(){
                return (
                    <div className="container">
                         <CounterList
                         counters={this.state.counters}
                            countUp={this.countUp}
                         />
                        <div>Total Inventory: {this.state.total}</div>
                    </div>
                )
            }
        }

            ReactDOM.render(
                <App/>,
                document.getElementById('root')
            );
    })();
    </script>

なるほど、component単位でJavaScriptで作っていくってわけね。少し理解した。