Web Programming with Dart. Moises Belchin Patricia Juberias

Transcription

1 Web Programming with Dart Moises Belchin Patricia Juberias

2 Web Programming with Dart Copyright 2015 by Moises Belchin and Patricia Juberias This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher s location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. ISBN-13 (pbk): ISBN-13 (electronic): Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Managing Director: Welmoed Spahr Lead Editor: Ben Renow-Clarke Technical Reviewer: Matthew Butler Editorial Board: Steve Anglin, Mark Beckner, Gary Cornell, Louise Corrigan, Jim DeWolf, Jonathan Gennick, Robert Hutchinson, Michelle Lowman, James Markham, Matthew Moodie, Jeff Olson, Jeffrey Pepper, Douglas Pundick, Ben Renow-Clarke, Gwenan Spearing, Matt Wade, Steve Weiss Coordinating Editor: Melissa Maldonado Copy Editor: Lori Cavanaugh and April Rondeau Compositor: SPi Global Indexer: SPi Global Artist: SPi Global Cover Designer: Anna Ishchenko Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit Apress and friends of ED books may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Special Bulk Sales ebook Licensing web page at Any source code or other supplementary material referenced by the author in this text is available to readers at For detailed information about how to locate your book s source code, go to

3 Contents at a Glance About the Authors... xv About the Technical Reviewer... xvii Acknowledgments... xix Introduction... xxi Chapter 1: Dart s Flightpath So Far...1 Part I: Getting Started Chapter 2: Setting up Dart Correctly...15 Part II: Dart Tools Chapter 3: Making the Most of the Dart Editor...33 Chapter 4: Using Pub and dart2js to Compile Applications to JavaScript...75 Chapter 5: Application Launches...87 Chapter 6: Using the Dart Pub Package Manager...99 Chapter 7: Optimizing for Dart VM and Dartium Chapter 8: Cleaning up with Dart Formatter Chapter 9: Generating Dart Code Documentation Chapter 10: Monitoring Your Applications with Observatory Part III: The Dart Language: Basics Chapter 11: The Dart Comment System Chapter 12: Understanding Operators and Expressions Chapter 13: Mastering Dart s Variables and Data Types iii

4 Contents at a Glance Chapter 14: Flow Control Statements Chapter 15: Working with Functions Chapter 16: A Syntax Summary and Cheat Sheet Part IV: The Dart Language: Advanced Chapter 17: Processing Exceptions and Error Control Chapter 18: Understanding Dart Classes Chapter 19: Implicit Interfaces and Abstract Classes Chapter 20: Implementing Generics and Typedefs Chapter 21: Using Dart s Libraries Chapter 22: Leveraging Isolates for Concurrency and Multi-Processing Chapter 23: Asynchronous Programming with Dart Chapter 24: An Advanced Syntax Summary Part V: Dart and Other Web Technologies Chapter 25: Integrating Dart and HTML Chapter 26: Integrating Dart and CSS Part VI: Dart and the Web Server Chapter 27: Combining Web Services with Dart Chapter 28: Dart on the Server Side Part VII: Dart s Future Chapter 29: Implementing Design Patterns and Creating Web Components Chapter 30: Developing a Dart App Index iv

5 Contents About the Authors... xv About the Technical Reviewer... xvii Acknowledgments... xix Introduction... xxi Chapter 1: Dart s Flightpath So Far...1 What is Dart?...1 Advantages to Using Dart...3 Dart s Origins...3 Converting From Other Programming Languages...5 Dart Names are Simpler and More Structured... 5 Searching for DOM Elements is Easier... 5 Dart Has Real Data Collections... 6 Constructors to Create New DOM Elements... 6 Dart Improves and Unifies the Events System... 7 Say Goodbye to Vendor Prefixes... 7 Future-Based APIs... 7 Libraries... 8 Cross-Browser Consistency... 8 Cascaded DOM Construction... 9 Why Dart is Perfect for Web Development...9 Summary...11 v

6 Contents Part I: Getting Started Chapter 2: Setting up Dart Correctly...15 vi Downloading and Installing the Software...15 Setting Up a Previous Version of Dart Editor Dart Editor and the Software Development Environment...20 Opening and Running an Example Creating Your First Application...24 Creating a Web Application Creating Command-Line Applications Summary...29 Part II: Dart Tools Chapter 3: Making the Most of the Dart Editor...33 The Dart Editor in Detail...33 Opening Some Examples...36 Creating Applications...38 Dart Editor Options and Main Views...40 Preferences and Views Running Applications...57 How Does this Sample Application Run? Advanced Examples Debugging Applications...64 Inspecting the SDK Summary...73 Chapter 4: Using Pub and dart2js to Compile Applications to JavaScript...75 Reviewing the Compliation Process...75 Pub build...77 dart2js...80 Pub Serve...84 Summary...86

7 Contents Chapter 5: Application Launches...87 Manage Launches...87 Dart Command-Line Launch...89 Dartium Launch...91 Chrome App Launch...92 Browser Launch...94 Android Mobile Launch...95 Summary...98 Chapter 6: Using the Dart Pub Package Manager...99 What is Pub?...99 Digging Deeper...99 Working With Commands and Packages Additional Pub Commands Summary Chapter 7: Optimizing for Dart VM and Dartium Dart Virtual Machine Dartium Checked Mode Summary Chapter 8: Cleaning up with Dart Formatter Dart Formatter Summary Chapter 9: Generating Dart Code Documentation docgen DocGen Options Summary vii

8 Contents Chapter 10: Monitoring Your Applications with Observatory viii Observatory Observatory and Command-Line Applications Observatory and Web Applications Summary Part III: The Dart Language: Basics Chapter 11: The Dart Comment System Comments Overview Inline Comments Block Comments Documentation Comments Markdown Links Block Styles Inline Styles Summary Chapter 12: Understanding Operators and Expressions An Introduction to Dart Operators Operator Types Arithmetic Equality and Relational Type Test Assignment Conditional Bit Others An Introduction to Expressions Conditional Logical Bit

9 Contents Equality Relational Bitwise Addition Multiplication Pre-Expressions and Post-Expressions Assignment How to Create Your Own Operators Summary Chapter 13: Mastering Dart s Variables and Data Types An Introduction to Variables and Data Types Variables Definition Types of Variables: Final and Const Data Types Numbers Strings Lists Maps Date and Time Summary Chapter 14: Flow Control Statements If and Else Switch Statement For Loop While Loop Summary ix

10 Contents Chapter 15: Working with Functions Defining Functions Positional Optional Parameters Named Optional Parameters Default Values Return Values Recursive Functions Summary Chapter 16: A Syntax Summary and Cheat Sheet Part IV: The Dart Language: Advanced Chapter 17: Processing Exceptions and Error Control Exceptions and Error Control Exceptions Types Error Types Exceptions and Error Definitions Summary Chapter 18: Understanding Dart Classes Instance Variables Constructors Methods Inheritance Variables and Static Methods Summary Chapter 19: Implicit Interfaces and Abstract Classes Summary x

11 Contents Chapter 20: Implementing Generics and Typedefs Generics Typedef Summary Chapter 21: Using Dart s Libraries Using Libraries Creating Libraries with Multiple Files Re-exporting Libraries Summary Chapter 22: Leveraging Isolates for Concurrency and Multi-Processing Summary Chapter 23: Asynchronous Programming with Dart What is Asynchronous Programming? Future Working with Future Stream Working with Stream Creating Asynchronous Functions Summary Chapter 24: An Advanced Syntax Summary Exceptions and Errors Classes Part V: Dart and Other Web Technologies Chapter 25: Integrating Dart and HTML Working with HTML Event Management Summary xi

12 Contents Chapter 26: Integrating Dart and CSS Working with CSS Visual Effects FadeIn and FadeOut Flashing Effect Expand and Collapse Items Summary Part VI: Dart and the Web Server Chapter 27: Combining Web Services with Dart Asynchronous HTTP Requests with Dart Using JSON in Dart Summary Chapter 28: Dart on the Server Side The I/O Dart Library Creating a Server Application Handling Requests Working with Processes Sockets Summary Part VII: Dart s Future Chapter 29: Implementing Design Patterns and Creating Web Components Web Components Polymer.dart What is the Shadow DOM? Working with Polymer.dart Summary xii

13 Contents Chapter 30: Developing a Dart App Designing the Application Creating the Application Coding the Application Summary Index xiii

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15 About the Authors Moises Belchin has worked with Dart from its inception in March 2011, is co-author of Aprende Dart, he contributes to Dart development and debugging, works with the community, and conducts seminars and developing the first point of reference about Dart for Spanish developers. Moises is a software engineer with 15 years of experience and thousands of lines of code under his belt; he s an expert in cloud computing solutions, big data, and web development. Patricia Juberias loves new technologies and graphic design. She is a multimedia engineer, specializing in information architecture, responsive design, user interface, and user experience. As a developer she has 10 years of experience with major programming languages and platforms, she has participated in numerous projects, is co-author of Aprende Dart, and collaborates in Dart spreading. xv

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17 About the Technical Reviewer Matthew Butler is an applications developer, focusing on web-based applications. He has over 14 years of experience in the industry in various roles. Matthew has contributed source code and documentation directly to Google s Dart programming language and has been active in the Dart community since He spends his evenings at home in Nova Scotia, Canada, with his wife Julie Ann and his boys Cody and Jaxon. You can contact him at xvii

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19 Acknowledgments We would like to thank the many people who helped to make this book possible. Moises and Patricia would like to thank his wife, her husband, pets and friends, for their very considerable patience during the evenings and weekends while we were working on this book. We would like to thank Ben, our lead editor; Melissa for guiding us through the process of building this book; James, Matthew, Dhaneesh, Lori and April, for the edits, reviews, and the final magic touch. Special thanks must go to Matthew Butler, our technical reviewer. We are indebted to him for his excellent, detailed reviewing of our work and the many helpful comments and suggestions he made that contributed decisively to the quality of this book. Thanks are also due to the Dartlang development team for creating such a wonderful programming language. xix

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21 Introduction Welcome to Web Programming with Dart. Early, in our careers we came to recognize how our world would change thanks to the Internet and especially to web applications. Every device we use in our daily lives uses the Internet intensively. If we consider the different sizes and characteristics of devices and the different operating systems available, we understand the complexity of software application development. Web applications can help us with that. You develop an application and deploy it through different devices and screen sizes, but to accomplish this task you need a programming language designed to understand the web development complexity and run in different platforms. The applications must be highly optimized and support numerous options: geo-localization, notifications, upload and play media files, or the interaction between users, among others. We can develop web applications with those functionalities but the only way to develop such complex applications is by using a high-level programming language specific to Web development with support for the latest web technologies. In this book you will master Dart, with a progressive and dynamic learning approach. It is one of the most complete books on Dart written so far and provides the basics of developing web applications using Dart, an object-oriented and structured language that supports interfaces, large hierarchy of classes, and optional typing. You will see examples and even develop your first complete web application, step by step. You will learn how to integrate Dart with CSS3 and HTML 5, combine Web Services with Dart, use Dart on the server side, implement design patterns and create web components. The book had been written with consideration for programmers who want to learn this new programming language but also for web designers because Dart can interoperate perfectly with HTML5 and CSS3. This book is oriented to developers and web designers who want to develop high-level web applications and are sick and tired of fighting with the creation of cross-platform web applications; for everyone who needs a new, yet familiar web programming language for modern web applications and really big projects; and for developers who need a typed language for a fast, secure, and easy development and debugging process. In the book we will travel from the most basic to the most complex functions of this language but we will also cover all the tools available to get the most of Dart. With this book you will know the language, how the tools work, and you will see the core functions and libraries. We will show you the history behind Dart and how it came to us. We will develop some UI animation samples for web, work with web services, server-side Dart applications, and the new Polymer.dart library for the new HTML UI web component generation. We will take a broad tour, showing the Dart basic and advanced functionalities. You will learn the tools that come with Dart SDK and the main, most important libraries. Additionally you will work with the newest Polymer.dart library for web component creation. You will be able to develop your own command-line and server-side applications and, of course, web applications with Dart. xxi