The spiral approach to software learning and development, which preserves a project history as a series of code snapshots or spirals, is used in this book.

The following three points are important in the spiral approach:

All of these three points are important in teaching and learning technologies.

Learning new software concepts and technologies is a challenging task. Learning in spirals, from simple to more advanced concepts but with concrete software applications, helps readers get a reasonable confidence level early on, and motivates them to learn by providing more useful applications. With each new spiral, the project grows and new concepts are introduced. A new spiral is explained with respect to the previous one. The difference between two consecutive spirals is that the next spiral has the new code introduced and the old code modified or deleted. This is named learning by anchoring to what we already understand. With a new spiral, we can come back to what we did previously and improve it. In this way, learning in spirals can touch the same topic several times, but each time with more details in a better version.

Learning Dart has 12 chapters. It begins with basic elements of Dart and it ends with a client/server application that uses MongoDB (http://www.mongodb.org/) for data persistence on the server side.

Chapter 1, Dart – A Modern Web Programming Language, helps you understand what Dart is all about. Dart is presented as a major step forward in the web programming arena.

Chapter 2, Getting to Work with Dart, lets you get a firm grasp on how to program in Dart. The code and data structures in Dart, and its functional principles, are explained by exploring practical examples.

Chapter 3, Structuring Code with Classes and Libraries, lets you understand how to use Dart classes to organize code. Dart libraries are introduced to show how complex software may be packaged.

Chapter 4, Modeling Web Applications with Model Concepts and Dartlero, enables you to design a small model graphically in the Model Concepts tool, which is developed in Dart. A model is then represented in Dart as several classes that inherit some data and operations from classes of the Dartlero model framework, also developed in Dart.

Chapter 5, Handling the DOM in a New Way, helps you to learn how to access HTML elements in Dart. Some elements will even be created in Dart and placed properly in the Document Object Model (DOM) of a web page. Dart will also handle user events, such as a click on a button. Finally, you will be able to create a simple game in Dart.

Chapter 6, Combining HTML Forms with Dart, lets you enter data in a form that will be validated by HTML5 and Dart. Then, the valid data will be saved in the local storage of a browser.

Chapter 7, Building Games with HTML5 and Dart, lets you create, step-by-step, a well-known memory game based on what you have learned already. Each step will be a new spiral represented as a complete project in Dart Editor. The first spiral will draw only a rectangle, while the last spiral will be a game that you may show to your friends.

Chapter 8, Developing Business Applications with Polymer Web Components, helps you to create several web components by using Polymer.dart. Those web components will be used in different sections of a single-page application. Three different projects with web components will be presented in this chapter.

Chapter 9, Modeling More Complex Applications with Dartling, explains how a graphical model can be transformed into a JSON document and then used to generate a complete model in Dart, by using the Dartling domain model framework together with its tools. Dartling follows the Model View Controller (MVC) pattern to separate a model from its views.

Chapter 10, MVC Web and UI Frameworks in Dart – An Overview, introduces you to different frameworks already developed in Dart. Because Dart is a brand new language, those frameworks are at early stages of their useful life.

Chapter 11, Local Data and Client-Server Communication, explains how you can store application data in a local database named IndexedDB, which will then be sent as a JSON document to a Dart server. Asynchronous programming with futures will also be covered in this chapter.

Chapter 12, Data-driven Web Applications with MySQL and MongoDB, explains how you can use database drivers to save (and load) data to (and from) a relational database and a NoSQL database. Data sent from a browser as a JSON document will easily be saved in MongoDB in the same JSON form. Two clients will exchange data with the server so that both of them will be up-to-date.

In order to benefit from this book, you need to have some basic experience in programming. It is also useful to have some understanding of HTML and CSS. What you really need to bring is your enthusiasm to learn how to become a web developer of the future. All the software used in the book are freely available on the Web:

One of the authors has already taught three times an introductory course to programming with some material from this book. The book also has its own website at http://www.learningdart.org/. Other educational resources for Dart can be found at http://ondart.me/.

The book is intended for web application programmers, game developers, and other software engineers. Because of its dual focus (Dart and HTML5), the book can appeal to both web developers who want to learn a modern way of developing web applications, and to developers who seek guidance on how to use HTML5. The audience would include mainstream programmers coming with an object-oriented background (Java, .NET, C++, and so on) as well as web programmers using JavaScript, who seek a more structured and tooled way of developing. Both groups would leverage their existing knowledge and expertise: the first, by offering them a way of developing modern web applications using techniques they already know, and the second, by giving them a more productive and engineered way of developing (business) web applications. The article at the following link describes well what Dart has to offer for the web developers of the future:

http://news.cnet.com/8301-1023_3-57613760-93/mixbook-sees-perfect-storm-for-googles-dart-language-q-a/.

In this book, you will find a number of styles of text that distinguish among different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "The calculateRabbits function calculates and returns an integer value; this is indicated by the word int preceding the function name."

A block of code is set as follows:

void main() {
  print("The number of rabbits increases as:\n");
  for (int years = 0; years <= NO_YEARS; years++) {
    rabbitCount = calculateRabbits(years);             
    print("After $years years:\t $rabbitCount animals");
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

void main() {
  print("The number of rabbits increases as:\n");
  for (int years = 0; years <= NO_YEARS; years++) {
    rabbitCount = calculateRabbits(years);
    print("After $years years:\t $rabbitCount animals");
}

Any command-line input or output is written as follows:

git clone git://github.com/dzenanr/collision_clones.git

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "You can change this behavior by navigating to Tools | Preferences | Run and Debug, and change the Break on Exceptions to None."

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