Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Learning Javascript Robotics
Learning Javascript Robotics

Learning Javascript Robotics: Design, build, and program your own remarkable robots with JavaScript and open source hardware

eBook
€8.99 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Table of content icon View table of contents Preview book icon Preview Book

Learning Javascript Robotics

Chapter 2. Working with Johnny-Five

In this chapter, we'll begin working with Johnny-Five to build our own robotics projects. We'll cover what makes Johnny-Five a great library for starting with robotics, and we will build our first robot. We'll learn how we can manipulate this robot in real time from the command line—a feat not easily replicated on other platforms! By the end of this chapter, you'll have an open understanding of the software involved, which will serve as a great foundation for more complicated hardware builds.

This chapter will cover the following topics:

  • How a Johnny-Five program works
  • Understanding events in Johnny-Five
  • Wiring an LED and making it blink
  • Using Read-Eval-Print-Loop (REPL)

What you'll need for this chapter

All you'll need for this chapter is your microcontroller (the examples here still use an Arduino Uno) and a small handful of LEDs—we'll be wiring only one LED, but you may want a couple of spares, in case one burns out.

How a Johnny-Five program works

In this section, we'll take a look at the internals of a Johnny-Five program in more detail, so we can start building more complex applications.

Objects, functions, and events

Johnny-Five programs work using an event-based structure, and there are three concepts to keep in mind: objects, functions, and events.

Objects tend to programmatically represent our physical electronic components and are usually constructed using the new keyword. A few examples of objects in Johnny-Five include the five object, which represents the Johnny-Five library, the Board object, which represents our microcontroller; and the LED object, which will programmatically represent our LED:

var led = new five.Led(11);

Functions are available for the objects we create and usually represent the actions that our robots can do. For instance, the LED object has an on() and off() function that turns the LED on and off:

led.on();
led.off();
led.blink();
led.stop();

Events are fired on objects...

Understanding events in Johnny-Five

The events in Johnny-Five are a very important concept—this is also a new concept, especially if you are used to low-level language programming. It's very similar to the idea of interrupts, but definitely strays away from the traditional robotics programming paradigm of an event loop. While you can create timers and loops in Johnny-Five, it highly encourages an event-based programming approach, which can need some practice.

Why events?

A question that gets asked a lot is, "Why event-based? Why not loop-based and interrupt-based as in previous methods?".

A lot of this has to do with the way robots work and the way we think about how we program robots. When you think about what you want a robot to do, you're less likely to think "Every X seconds, I want to check for A and start task B..." and you are more likely to think "When Y happens, I want to start event C...".

The event-based system in Johnny-Five works really...

Wiring up an external LED

For our first hardware project, we're going to wire an LED to the Arduino. An LED, or a Light Emitting Diode, is a component that lights up when electric current is passed through it. They come in many colors and sizes and are one of the most easy-to-use and versatile components in hobbyist robotics.

Setting up the hardware

First, take an LED. We'll determine the positive and negative leads of the LED—for this component, it's straightforward: the positive lead is longer than the negative lead.

Setting up the hardware

Determining the positive and negative ends of an LED

To wire the LED to an Arduino, place the positive lead on pin 11 and the negative lead on the pin marked GND, just like in the following diagram:

Setting up the hardware

Wiring up our LED

You can also use a breadboard if you wish to—it will look like the following:

Setting up the hardware

Wiring an LED with a breadboard

Now that we've wired up the LED, we're going to make it blink as we did in the last chapter. The script looks very familiar...

Using the Read-Eval-Print-Loop (REPL)

The Read, Eval, Print Loop, or REPL, is a concept relative to many scripting languages, but it is new to libraries, and definitely new to robotics. Think about how you alter the state in a typical Arduino program: you modify the source code, re-load it onto the board, and wait for it to run.

However, due to the way Johnny-Five works, we can modify the state of our robot code while the code is running. This is because we use Firmata—the board is just a thin client that reacts to instructions from our node program, so if we let our Node programs send different instructions, we can change how our robot works in real time.

The way to do this in a Johnny-Five program is by injecting components into the REPL, which allows us to use them.

Making components available to the REPL

We're going to modify our script from the previous section in order to manipulate our LED. To do this, we're going to use the this.repl.inject() function. The this keyword...

What you'll need for this chapter


All you'll need for this chapter is your microcontroller (the examples here still use an Arduino Uno) and a small handful of LEDs—we'll be wiring only one LED, but you may want a couple of spares, in case one burns out.

Left arrow icon Right arrow icon

Description

There has been a rapid rise in the use of JavaScript in recent times in a variety of applications, and JavaScript robotics has seen a rise in popularity too. Johnny-Five is a framework that gives NodeBots a consistent API and platform across several hardware systems. This book walks you through basic robotics projects including the physical hardware builds and the JavaScript code for them. You'll delve into the concepts of Johnny-Five and JS robotics. You'll learn about various components such as Digital GPIO pins, PWM output pins, Sensors, servos, and motors to be used with Johnny-Five along with some advanced components such as I2C, and SPI. You will learn to connect your Johnny-Five robots to internet services and other NodeBots to form networks. By the end of this book, you will have explored the benefits of the Johnny-Five framework and the many devices it unlocks.

What you will learn

  • Familiarise yourself with JohnnyFive Read, Eval, and Print Loop (REPL) to modify and debug robotics code in real time
  • Build robots with basic output devices to create projects that light up, make noise, and more
  • Create projects with complex output devices, and employ the JohnnyFive API to simplify the use of components that require complex interfaces, such as I2C
  • Make use of sensors and input devices to allow your robotics projects to survey the world around them and accept input from users
  • Use the Sensor and Motor objects to make it much easier to move your robotics projects
  • Learn about the Animation API that will allow you to program complex movements using timing and key frames
  • Bring in other devices to your JohnnyFive projects, such as USB devices and remotes
  • Connect your JohnnyFive projects to external APIs and create your own Internet of Things!
Estimated delivery fee Deliver to Austria

Premium delivery 7 - 10 business days

€17.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Nov 25, 2015
Length: 160 pages
Edition : 1st
Language : English
ISBN-13 : 9781785883347
Vendor :
Netscape
Category :
Languages :
Concepts :
Tools :

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Estimated delivery fee Deliver to Austria

Premium delivery 7 - 10 business days

€17.95
(Includes tracking information)

Product Details

Publication date : Nov 25, 2015
Length: 160 pages
Edition : 1st
Language : English
ISBN-13 : 9781785883347
Vendor :
Netscape
Category :
Languages :
Concepts :
Tools :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 87.97
Javascript Unlocked
€24.99
Raspberry Pi Robotic Blueprints
€37.99
Learning Javascript Robotics
€24.99
Total 87.97 Stars icon
Banner background image

Table of Contents

10 Chapters
1. Getting Started with JS Robotics Chevron down icon Chevron up icon
2. Working with Johnny-Five Chevron down icon Chevron up icon
3. Using Digital and PWM Output Pins Chevron down icon Chevron up icon
4. Using Specialized Output Devices Chevron down icon Chevron up icon
5. Using Input Devices and Sensors Chevron down icon Chevron up icon
6. Moving Your Bot Chevron down icon Chevron up icon
7. Advanced Movement with the Animation Library Chevron down icon Chevron up icon
8. Advanced Components – SPI, I2C, and Other Devices Chevron down icon Chevron up icon
9. Connecting NodeBots to the World, and Where to Go Next Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Top Reviews
Rating distribution
Full star icon Full star icon Full star icon Full star icon Half star icon 4.3
(6 Ratings)
5 star 83.3%
4 star 0%
3 star 0%
2 star 0%
1 star 16.7%
Filter icon Filter
Top Reviews

Filter reviews by




Andrew Connell Dec 18, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I'm a seasoned JavaScript developer and aspiring hardware guy for my own personal projects. Having heard Kassandra on a podcast episode or two, I wanted to pick this book up. I found it very easy to grok and pickup the concepts. I am more of a Raspberry Pi guy and all the projects used the Arduino Uno - my only "complaint" that it should have been more visible in the marketing / cover - however I walked away placing an order for the Uno, something I've wanted to learn! All the projects were super simple to understand and implement... as a tech author I know how much work goes into this, but hoping for something that goes even deeper for her next work!
Amazon Verified review Amazon
Rick Waldron Nov 30, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This book is a great way to "break in" to JavaScript Robotics with Johnny-Five. Each chapter walks you through the basics and then illustrates how to build something with with what you've learned—which is a great strategy!
Amazon Verified review Amazon
Roberto M. Pensotti Apr 19, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
If you want to learn programming for robots, or micro controllers in general, this is the book.JavaScript on NodeJS is the best language for this type of application.Well illustrated, well documented..Excellent!
Amazon Verified review Amazon
K Feb 11, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This book assumes quite a bit less of your robotics experience than it does of your experience with JavaScript. It focuses a great deal on the excellent Johnny Five library for Raspberry Pi and Arduino. It helps you to learn the basics of motor control as well as sensor information through GPIO. If you already have JavaScript experience, this is definitely the best foray into extending your ability into the world of robotics.
Amazon Verified review Amazon
Grayson Nov 30, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
The animation chapter alone makes this a great book. Great introduction to nodebots and generally working with electronics + javascript. Presented in an approachable manner with clear explanations.
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is the delivery time and cost of print book? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela
What is custom duty/charge? Chevron down icon Chevron up icon

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order? Chevron down icon Chevron up icon

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges? Chevron down icon Chevron up icon

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

  • If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
  • Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.
How can I cancel my order? Chevron down icon Chevron up icon

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela