binarycounter.js

var five = require("johnny-five");
var board = new five.Board();

function outputBinary(number, leds) {
    var states =  [
         number & 1,
         number & 2,
         number & 4
    ];

    for (var i = 0; i < 3; ++i) {
        if (states[i]) {
            leds[i].on();
        } else {
            leds[i].off();
        }
    }
}

board.on("ready", function() {
    var ledLocations = [9, 10, 11];
    var leds = [];
    var button = new five.Button(2);

    var counter = 0;

    button.on("press", function() {
        outputBinary(counter, leds);
        ++counter;
    });

    ledLocations.forEach(function(value) {
        var led = new five.Led(value);
        leds.push(led);
    });

    this.repl.inject({
        leds: leds,
        button: button
    });
});