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DART Cookbook

DART Cookbook

By : Ivo Balbaert
4 (2)
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DART Cookbook

DART Cookbook

4 (2)
By: Ivo Balbaert

Overview of this book

If you are a Dart developer looking to sharpen your skills, and get insight and tips on how to put that knowledge into practice, then this book is for you. You should also have a basic knowledge of HTML, and how web applications with browser clients and servers work, in order to build dynamic Dart applications.
Table of Contents (13 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Working with Dart Tools
1. Working with Dart Tools
Introduction
Configuring the Dart environment
Setting up the checked and production modes
Rapid Dart Editor troubleshooting
Hosting your own private pub mirror
Using Sublime Text 2 as an IDE
Compiling your app to JavaScript
Debugging your app in JavaScript for Chrome
Using the command-line tools
Solving problems when pub get fails
Shrinking the size of your app
Making a system call
Using snapshotting
Getting information from the operating system
2
2. Structuring, Testing, and Deploying an Application
2. Structuring, Testing, and Deploying an Application
Introduction
Exiting from an app
Parsing command-line arguments
Structuring an application
Using a library from within your app
Microtesting your code with assert
Unit testing a Polymer web app
Adding logging to your app
Documenting your app
Profiling and benchmarking your app
Publishing and deploying your app
Using different settings in the checked and production modes
3
3. Working with Data Types
3. Working with Data Types
Introduction
Concatenating strings
Using regular expressions
Strings and Unicode
Using complex numbers
Creating an enum
Flattening a list
Generating a random number within a range
Getting a random element from a list
Working with dates and times
Improving performance in numerical computations
Using SIMD for enhanced performance
4
4. Object Orientation
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4. Object Orientation
Introduction
Testing and converting types
Comparing two objects
Using a factory constructor
Building a singleton
Using reflection
Using mixins
Using annotations
Using the call method
Using noSuchMethod
Making toJSON and fromJSON methods in your class
Creating common classes for client and server apps
5
5. Handling Web Applications
5. Handling Web Applications
Introduction
Responsive design
Sanitizing HTML
Using a browser's local storage
Using application cache to work offline
Preventing an onSubmit event from reloading the page
Dynamically inserting rows in an HTML table
Using CORS headers
Using keyboard events
Enabling drag-and-drop
Enabling touch events
Creating a Chrome app
Structuring a game project
Using WebGL in your app
Authorizing OAuth2 to Google services
Talking with JavaScript
Using JavaScript libraries
6
6. Working with Files and Streams
6. Working with Files and Streams
Introduction
Reading and processing a file line by line
Writing to a file
Searching in a file
Concatenating files
Downloading a file
Working with blobs
Transforming streams
7
7. Working with Web Servers
7. Working with Web Servers
Introduction
Creating a web server
Posting JSON-formatted data
Receiving data on the web server
Serving files with http_server
Using sockets
Using WebSockets
Using secure sockets and servers
Using a JSON web service
8
8. Working with Futures, Tasks, and Isolates
8. Working with Futures, Tasks, and Isolates
Introduction
Writing a game loop
Error handling with Futures
Scheduling tasks using Futures
Running a recurring function
Using isolates in the Dart VM
Using isolates in web apps
Using multiple cores with isolates
Using the Worker Task framework
9
9. Working with Databases
9. Working with Databases
Introduction
Storing data locally with IndexedDB
Using Lawndart to write offline web apps
Storing data in MySQL
Storing data in PostgreSQL
Storing data in Oracle
Storing data in MongoDB
Storing data in RethinkDB
10
10. Polymer Dart Recipes
10. Polymer Dart Recipes
Introduction
Data binding with polymer.dart
Binding and repeating over a list
Binding to a map
Using custom attributes and template conditionals
Binding to an input text field or a text area
Binding to a checkbox
Binding to radio buttons
Binding to a selected field
Event handling
Polymer elements with JavaScript interop
Extending DOM elements
Working with custom elements
Automatic node finding
Internationalizing a Polymer app
11
11. Working with Angular Dart
11. Working with Angular Dart
Introduction
Setting up an Angular app
Using a controller
Using a component
Using formatters as filters
Creating a view
Using a service
Deploying your app
12
Index
Index

Testing and converting types

Everything in Dart is an object and has a type; an instance of a class descended from an object through a single inheritance chain, even null is of type Null. Type annotating a variable is not required in Dart, for example, contrary to Java. In this case, the variable is declared with var and is of type dynamic. Values sometimes have to be converted from one type to another. In order to avoid runtime type errors when the conversion fails, we can test if the value is of the type we want to cast it to before the conversion. For the code examples, refer to types.dart.

How to do it...

We can test and convert types with the help of the following steps:

  1. We can test and show the type of an object, as shown in the following code:
    void main() {
  var p = new Person();
  p.name = "Joe";
if (p is Person) {
     print('p is called ${p.name}');
     print('p is of type ${p.runtimeType}');                     } else {
   // p has value null and is...

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