Search icon CANCEL
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
MASTERING KNOCKOUTJS
MASTERING KNOCKOUTJS

MASTERING KNOCKOUTJS: Use and extend Knockout to deliver feature-rich, modern web applications

eBook
€22.99 €32.99
Paperback
€41.99
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
Table of content icon View table of contents Preview book icon Preview Book

MASTERING KNOCKOUTJS

Chapter 2. Extending Knockout with Custom Binding Handlers

Knockout's standard bindings are great. They solve most of the general problems you are likely to encounter when developing web apps. But there is always the need to provide something special, whether you are working on your own library or just trying to add a bit of style to your app. When that happens, you will want to provide that functionality through the same binding system you are using everywhere else. Luckily, Knockout makes extending this system easy. In this chapter, we will be looking at how to make our own binding handlers. We will be covering the following topics:

  • What a binding handler contains
  • Creating new binding handlers
  • Using custom binding handlers to integrate with third-party libraries
  • Managing binding contexts
  • Using the containerless control flow syntax with custom bindings

Creating custom binding handlers for new and more complex HTML interactions is a key to developing feature-rich applications....

The data binding pattern

This section is primarily philosophical. If you feel like you already have a solid understanding of the what and why behind the Model-View-ViewModel (MVVM) pattern and binding handlers, then you might want to skip to the next section, Components of a binding handler.

Okay, let's talk about patterns and practices. If you haven't worked with WPF before, then the MVVM pattern is probably the most confusing thing about Knockout. MVVM is a pattern that came out of Microsoft. It doesn't get a lot of attention outside the .NET community, and it's similar enough to the far more popular MVC pattern because of which confusion is nearly guaranteed.

In MVVM, the viewmodel is supposed to represent an abstraction of the view. Consider these two lists of message threads in iOS:

The data binding pattern

They both show a list of threads, and each thread contains a title showing the person it is with, an excerpt from the most recent message, and a timestamp. A thread can be selected or...

Components of a binding handler

Binding handlers are defined by adding objects to the ko.bindingHandlers object, just like extenders. They are composed of an init and an update function.

The init function runs when the binding is first applied to the element either when ko.applyBindings is called or when the element is created by a control flow binding, such as template or foreach. It should be used for all one-time work such as attaching event handlers or disposal callbacks to the element.

The update function runs just after init does, when the binding is first applied. It runs again anytime when any observable dependencies are changed. The update function determines its dependencies just like a computed observable does. If an observable is accessed when an update runs, it subscribes to that observable. The update function should be used to keep the UI in sync with changes from the viewmodel:

ko.bindingHandlers.yourBindingName = {
    init: function(element, valueAccessor, allBindings, viewModel...

Simple binding handlers

Binding handlers can range from very simple to whole applications by themselves. As the purpose of binding handlers is to translate between the presentation layer (HTML) and the viewmodel (JavaScript), the binding handler's complexity is directly related to the complexity of the UI interaction and the bound data. Simple tasks such as hiding or showing an element with animation will have very thin handlers, while data binding on an interactive map element will require much more logic.

Animated binding handlers

As DOM interaction in the primary use case for jQuery, and given its popularity, it is not uncommon to use jQuery inside Knockout binding handlers. The canonical custom binding handler example from the Knockout documentation is a binding to hide and show elements, with the jQuery's slideUp and slideDown methods, instead of using the standard visible binding to switch them on and off:

ko.bindingHandlers.slideVisible = {
    init: function(element, valueAccessor...

Advanced binding handlers

So far, we've been looking at binding handlers that handle one or two properties and result in a fairly simple single-purpose control. In the previous example, we started looking at binding handlers that created new child elements, and this technique allows us to create much more complex binding behaviors. Bindings can also interact with complex elements such as charts or map controls (for example, a Google Maps widget), providing a clean API that the viewmodel can interact with.

Binding complex data with charts

The first time we looked at integrating with a third-party control was with a single-property two-way binding to a datepicker. Any time we are working with third-party UI tools, the goal is to abstract them away from the view and the viewmodel through bindings; even when those tools are for complex structures such as charts.

Charts.js (http://www.chartjs.org) is a popular JavaScript library built to display data in, you guessed it right, graphical charts...

Containerless syntax with custom bindings

In the first chapter, we spoke about containerless bindings; bindings applied through comments that created a virtual container around their "child" nodes. Now that we have a good understanding of how to create our own binding handlers, it's time to learn how to make them containerless bindings.

First, we are going to make a normal binding and then look at what we need to do to allow it to support the virtual elements. Let's say you want a binding that sorts its children elements. It would need to loop through them, check some property, and then rearrange the DOM so they were in order. Normally, sorting would be achieved by using a foreach binding against a sorted observableArray property, but we're going to make a sort binding that sorts on the width of the DOM node, which takes into account any CSS that may have affected it. The viewmodel would have a hard time getting this information to determine the proper sort order...

Summary

If you take away one thing from all these examples, it should be that binding handlers are solely responsible for interaction with the DOM. In our first example, we made the slideVisible binding as an animated replacement for the standard visible binding. This change from the normal "instant" hide and show to the "animated" hide and show was completely decoupled by our viewmodel. This is beneficial because it keeps these two pieces completely separated, allowing them to develop and evolve independently.

In this chapter, we covered simple and complex binding handlers, binding context management, and using the virtual elements API to support containerless bindings. In the next chapter, we will be looking at preprocessors for bindings and nodes.

Left arrow icon Right arrow icon

Description

If you are an experienced JavaScript developer who is looking for new tools to build web applications and get an understanding of core elements and applications, this is the book for you. A basic knowledge of DOM, JavaScript, and KnockoutJS is assumed.
Estimated delivery fee Deliver to Ireland

Premium delivery 7 - 10 business days

€23.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Nov 26, 2014
Length: 270 pages
Edition : 1st
Language : English
ISBN-13 : 9781783981007
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
Estimated delivery fee Deliver to Ireland

Premium delivery 7 - 10 business days

€23.95
(Includes tracking information)

Product Details

Publication date : Nov 26, 2014
Length: 270 pages
Edition : 1st
Language : English
ISBN-13 : 9781783981007
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 103.97
KnockoutJS Web Development
€24.99
Mastering JavaScript Design Patterns
€36.99
MASTERING KNOCKOUTJS
€41.99
Total 103.97 Stars icon

Table of Contents

10 Chapters
1. Knockout Essentials Chevron down icon Chevron up icon
2. Extending Knockout with Custom Binding Handlers Chevron down icon Chevron up icon
3. Extending Knockout with Preprocessors and Providers Chevron down icon Chevron up icon
4. Application Development with Components and Modules Chevron down icon Chevron up icon
5. Durandal – the Knockout Framework Chevron down icon Chevron up icon
6. Advanced Durandal Chevron down icon Chevron up icon
7. Best Practices Chevron down icon Chevron up icon
8. Plugins and Other Knockout Libraries Chevron down icon Chevron up icon
9. Under the Hood 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 4.7
(6 Ratings)
5 star 83.3%
4 star 0%
3 star 16.7%
2 star 0%
1 star 0%
Filter icon Filter
Top Reviews

Filter reviews by




Christopher Fleming Sep 08, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I am experienced with knockout and yet this well written book yielded many new priceless undiscovered bits of information. This compliments and expands on the excellent knockout site and a must for any developer serious about mastering knockout end-to-end.
Amazon Verified review Amazon
Christian Del Bianco Oct 25, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Clear explanations, NOT boring at all. Correlated with many examples. I also appreciate the introduction to Durandal and RequireJS frameworks.
Amazon Verified review Amazon
Evan Nelson Jan 27, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
In my experience, programming books always seem to have one of two problems: 1) they are targeted at first-time programmers and thus are way too dumbed down, or 2) they are targeted at people who are already experts in the subject and just need some sort of reference. Where are all the books for experienced developers who were able to sort out the basics of TechnologyX on their own, but who need a practical guide for the more advanced topics?For me, this book hits that very important sweet spot. It does not assume its audience to be beginning programmers, but neither does it throw around terms like "polyfill" without giving some sort of definition. Every chapter is littered with code samples, each one following logically from the previous. The samples are concise, including only the relevant details, but full context can be found by looking at the author's github repository (every sample has its own branch in the repo). Each technique that the book teaches you is backed by a real-world example as opposed to a generic "FooBarBaz" example, making it easy to understand *why* you would do something, instead of just telling you *how*.Overall, a great resource for anyone who already understands the basics of web development wants to learn to use Knockout to its fullest extent.
Amazon Verified review Amazon
Travis Wilson May 10, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This book actually covers expert-level Knockout. A must buy if you're serious about taking it to the next level.
Amazon Verified review Amazon
Christian Del Bianco Jul 08, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Very detailed book about knockout. Also, there is an insteresting part about Durandal - knockout framwork for SPA. I found it very usefull. Be aware that this book is not an intro. It is an advance level.
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