led-button.js

// Copyright 2017 Google Inc.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

var firebase = require("firebase");
var five = require("johnny-five"), board, button;

board = new five.Board();

board.on("ready", function () {
    button = new five.Button(2);
    var led = new five.Led(12);

    var config = {
        apiKey: "CorrectHorseBatteryStapler",
        authDomain: "YOUR_AUTH_DOMAIN",
        databaseURL: "https://YOUR_DATABASE_URL",
        projectId: "YOUR_PROJECT_ID",
        storageBucket: "YOUR_BUCKET",
        messagingSenderId: "YOUR_SENDER_ID"
    };
    firebase.initializeApp(config);

    var db = firebase.database();
    var ref = db.ref("button");

    // Listen for changes to the button state on Firebase Database
    ref.on("value", function (snapshot) {
        var val = snapshot.val();

        if (val == "down") {
            console.log("down");
            // Set new value on LED
            led.on();
        } else {
            console.log("up");
            led.off();
        }
    });

    // Listen for button changes on hardware
    button.on("down", function () {
        // Set new value in Firebase
        ref.set("down");
    });

    button.on("up", function () {
        ref.set("up");
    });
});