critical-leddemo/src/app.js

import React from 'react';
import io from 'socket.io-client';

export default class App extends React.Component {
    constructor(props) {
        super(props);

        this.state = {
            ioState: {
                dout: [false],
            },
            socket: io.connect()
        }
    }

    componentDidMount() {
        this.connect();
    }

    componentWillUnmount() {
        this.setState({socket: this.state.socket.removeAllListeners()});
    }

    connect() {
        let socket = this.state.socket;

        socket.on('connect', () => {
            console.log('connected');
        });

        socket.on('message', (data) => {
            console.log(data);
        });
    }

    doutSet(pin, value) {
        this.setState({
            ioState: {
                ...this.state.ioState,
                dout: this.state.ioState.dout.map((x, i) => i == pin ? value : x),
            },
        });
    }

    render() {
        return (
            <div className="ui text container">
                <div className="ui stackable two column grid">
                    <div className="one column row">
                        <div className="center aligned column">
                            <div className="ui basic segment">
                                <img className="ui left floated small image" src="http://criticalcontrol.com/wp-content/themes/cces/images/logo.png" />
                                <span className="ui medium header">LED Toggle Demo</span>
                            </div>
                        </div>
                    </div>
                    <div className="column">
                        <div className="ui segment">
                            <div className="ui top attached label">Digital Out</div>
                            <div className="ui two column middle aligned grid">
                                <div className="twelve wide column">
                                    <div className="ui right pointing label">
                                          DO1
                                    </div>
                                    <div className="ui buttons">
                                      <button onClick={() => this.doutSet(0, true)} className="ui red button">On</button>
                                      <button onClick={() => this.doutSet(0, false)} className="ui button">Off</button>
                                    </div>
                                </div>
                                <div className="four wide right aligned column">
                                    {!this.state.ioState.dout[0] && <i className="bordered inverted disabled idea big icon"></i>}
                                    {this.state.ioState.dout[0] && <i className="bordered inverted red idea big icon"></i>}
                                </div>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
       );
    }
}