Nowadays, there are many flavors for frontend frameworks and libraries in the market. There are frameworks you can use if you only want to manipulate the Document Object Model (DOM), frameworks used only for styling, frameworks for user-friendly components, frameworks used to design your project, and so on. Also there is Ext JS, a framework used to create Rich Internet Applications (RIA), but it has many other features than just pretty components.
In this book, we are going to learn how to develop an application from the beginning to the end with Ext JS 5, also covering some pieces of the backend required to make our application work. We will learn how to use Ext JS with hands-on examples covering some components, how they work, and how to use them in each chapter.
But first, you are going to learn what Ext JS is capable of if this is the first time you have come into contact with the framework.
Amazingly, the answer is positive to all the preceding questions! As we can see, Ext JS is a complete frontend framework. The mastermind company behind Ext JS is Sencha Inc. (http://sencha.com).
Sencha Ext JS also has a cousin called Sencha Touch. It also has the amazing features we just mentioned, but focuses on the mobile cross-platform world. We will talk very briefly about Ext JS and Sencha Touch in later chapters of this book.
Usually, we want to use MySQL, Oracle, MS Server or any other database. To be able to store information in a database, we need to use a server-side language, such as PHP, Java, C#, Ruby, Python, Node.js, and so on. Ext JS will communicate with the server-side language (or web services), and the server will connect to the database or any other storage (documents repository, for example).
The following diagram exemplifies the architecture of an application developed with Ext JS:
We have already mentioned some Ext JS capabilities. Let's take a brief look at each one of them. But first, if you want to take a look at the official Sencha Ext JS webpage, visit http://www.sencha.com/products/extjs/.
Basic tutorial and Ext JS overview: http://www.sencha.com/products/extjs/up-and-running
Ext JS guides: http://docs.sencha.com/extjs/5.0/
Ext JS documents: http://docs.sencha.com/extjs/5.0/apidocs/
Ext JS examples: http://dev.sencha.com/ext/5.0.1/examples/index.html
Forum (become part of the community): http://www.sencha.com/forum/
Ext JS also follows a naming convention. If you are familiar with OO programming, you are probably familiar with the naming conventions of Ext JS as well. For example, class names are alphanumeric, starting with an uppercase character, and and then the rest of the letters are in CamelCase. For example, if we want to create a class to represent the client details, we could name it
ClientDetails. Method and attribute names start with a lowercase character and then the rest of the letters are in CamelCase. For example,
retrieveClientDetails() is a good name for a method and
clientName is a good name for an attribute.
Ext JS is organized in packages as well. Packages are a way of organizing the code that has the same purpose. For example, in Ext JS, there is a package called
data that handles everything related to data in the framework. There is a packaged named
grid that contains all the code related to GridPanels.
For more information about the class system, please read http://docs.sencha.com/extjs/5.0/core_concepts/classes.html.
The main reason some people consider using Ext JS is probably because of its rich and user-friendly components. Ext JS contains some of the most used components in web applications, such as forms, grids, and trees. We can also use charts that are touch-friendly (meaning they work on touchscreens as well) and the drawing package that uses all the advantages of Scalable Vector Graphics (SVG) and HTML5.
You can checkout the official Sencha Ext JS examples page at http://dev.sencha.com/extjs/5.0.0/examples/index.html to have an idea of what we can do with the examples.
The Component class is the parent class for all Ext JS widgets. Below the Component class, we have the Container class. The Container class might contain other components. For example, let's take a look at the following GridPanel:
Grid Panel class extends from the
Panel class, a very popular component in Ext JS. The
Panel class supports headers, docked items (toolbars), and it contains a body space. Subclasses of the
Panel class, such as
Form, are panels, but instead of the body, they have a specialized
View class that is responsible for rendering the specific information. For example, the
View class of a
Grid panel is specialized in rendering the Grid Column; the
View class of a
Tree Panel is specialized in rendering hierarchical information, and the
View class of a
Form panel (called BasicForm) is specialized in rendering form fields.
To create a grid, the developer needs to declare at least two configurations:
Store class organizes a collection of data in Ext JS, and it is responsible for feeding the grid with the information to be displayed. We will explore it when we discuss the data package.
The grid component can be used as a plain and simple data grid, with only the information records being displayed. Or, if we have a large amount of data, we can use its paging capabilities, or we can also use a Big Data Grid if we really have a large amount of data. There are also other features such as grouped header grid (also known as Pivot Grid); we can also have a grid with locked columns or even with widgets, such as chats, as demonstrated by the previous screenshot. Among other features, we can also sort and filter the information inside the grid and use some of its plugins to accomplish tasks such as expanding the rows to display more information without popups, using checkboxes to select rows and automatic numbered rows as well. And there is more: the grid component also supports editing by opening a small pop-up row so that you can edit the information directly in the grid. The grid also supports cell editing, which is similar to what we can do in MS Excel—edit the information by double-clicking on a cell.
For more information, please take a look at http://docs.sencha.com/extjs/5.0/apidocs/#!/api/Ext.grid.Panel and http://docs.sencha.com/extjs/5.0/components/grids/grids.html.
Trees display hierarchical data, such as a file directory. A tree's data comes from a TreeStore or is predefined in the
root configuration. The tree also supports sorting and filtering, select a row using checkboxes, and we can also mix a tree with a grid and use the TreeGrid component.
It also supports plugins such as drag and drop between trees.
For more information, please take a look at http://docs.sencha.com/extjs/5.0/apidocs/#!/api/Ext.tree.Panel and http://docs.sencha.com/extjs/5.0/components/trees.html.
Next, we have the form component. We can implement powerful forms using text, area, and number fields. We can also use the date/month picker, checkboxes, radio buttons, comboboxes, and even file upload. All fields have the basic native validation support (with error messages to the user), such as mandatory fields and minimum and maximum value or length, but we can easily customize and create custom validation (IP address for example).
For more information, please take a look at http://docs.sencha.com/extjs/5.0/apidocs/#!/api/Ext.form.Panel and http://docs.sencha.com/extjs/5.0/components/forms.html.
We also have the charts. We can build column, bar, line, area, scatter, pie, radial, gauge, and even financial charts. We can have basic, stacked, multi-axis, and 3D charts as well. The charts are also fed by a Store.
And of course, there are basic components that will help our application look even better, such as menus, tabs, panels, windows, alerts, toolbars, and so on. The components have Web Accessibility Initiative – Accessible Rich Internet Applications (WAI-ARIA) support and also support right-to-left languages.
Seems nice, right? We will cover most of the components and its capabilities throughout the examples of this book.
Ext JS supports different possibilities. It also has a great layout manager (only when we create an Ext JS application using its base component, the Viewport. For components that are used in a standalone form (rendered in a
<div> tag, the layout manager does not work when you decrease the size of the browser window).
Some of the layouts supported are Absolute layout (where we need to use the absolute x and y positions of the component in the screen or within the component); Accordion layout, Border layout, Card layout, Center layout, Column layout, Fit layout, Hbox and VBox layouts, and Table layouts.
The layouts that are most used in applications are Border, Card, Fit, and HBox and VBox. We will cover different layouts through the examples of this book as well.
For more information, please take a look at http://dev.sencha.com/ext/5.0.1/examples/kitchensink/#layouts and the
layout.container package at http://docs.sencha.com/extjs/5.0/apidocs/#!/api/Ext.layout.container.Absolute.
Server-side languages usually support data well. In Java, PHP, C#, and other languages, we can create entities known as Plain Old Java Object (POJOs), Persistent Domain Objects (PDOs), and Value Objects (VOs), and other names that we usually give to these entities. Ext JS supports data, so we represent entities in the frontend as well.
There are basically three major pieces:
Model: This represents the entity. It can represent a class we have on the server side or a table from the database. Model supports fields, validations, associations (OneToOne, OneToMany, ManyToMany).
Proxy: This represents the way we are going to connect to the server (or a local storage). It can be Ajax, REST, JSONP, Memory, or HTML5 LocalStorage. Inside the proxy, we can define
Readerattribute is responsible for decoding the data we receive from the server (we can define it if it is JSON or XML, and we can also define its format). The
Writerattribute is responsible for encoding the data to be sent to the server; it can be JSON or XML, and we can also define its format. The Proxy can be placed inside a Model or a Store.
For more information please read http://docs.sencha.com/extjs/5.0/core_concepts/data_package.html.
While working with Ext JS, we can choose between two architectures for our frontend code: Model View Controller (MVC) and Model View ViewModel (MVVM). There is also a third option, which is a hybrid between MVC and MVVM.
Throughout this book, we are going to learn more about MVC, MVVM, and also the hybrid approach.
For more information please read http://docs.sencha.com/extjs/5.0/application_architecture/application_architecture.html.
For more information please read http://docs.sencha.com/extjs/5.0/core_concepts/theming.html.
Ruby 1.8 or 1.9: The current version of Ruby is 2.x at the time of writing this. To be able to create an Ext JS application, we need to have Ruby 1.8 or 1.9 installed. Ruby is required because the theming engine used by Ext JS is based on Sass and Compass, which are Ruby gems. To download and install Ruby, please follow the instructions at https://www.ruby-lang.org/en/installation/.
Sass and Compass: These are not CSS frameworks. Sass is a new way of writing CSS. It is possible to use variables and define functions and mixins. It is an alternative to Less (maybe you have worked with Less or heard about it—Sass is very similar). After downloading and installing Ruby, please install Sass as well. The instructions can be found at http://sass-lang.com/install (follow the command-line instructions). Compass is a Sass framework and is also required. Please install it as well from http://compass-style.org/install/. Sass and Compass are the heart of the Ext JS theming engine. All custom CSS we are going to create for our application will be compiled by Sass/Compass as well.
Java JDK: If you are a Java developer, you probably have the Java JDK installed already. If not, please download and execute the installer at http://www.oracle.com/technetwork/articles/javase/index-jsp-138363.html. After installing the Java JDK, we also need to configure the
JAVA_HOMEenvironment variable. Instructions can be found at http://goo.gl/JFtKHF. The Java JDK is required because of ANT, our next step.
Apache ANT: The Sencha Cmd engine to create the application and build it is based on ANT, a Java library. We need to download ANT from http://ant.apache.org/bindownload.cgi, unzip it to a directory of our choice, and set the
ANT_HOMEenvironment variable (http://ant.apache.org/manual/install.html).
We can check whether we have the correct environment by executing the following commands in a terminal application:
Note that the Ruby version installed is 2.x, but as long as you have a 1.8 or 1.9 compatible version in your classpath, you should be OK.
The last step is a web server. The simplest one that we can use to execute the examples of this book is Apache Xampp. Download and follow the installation instructions at https://www.apachefriends.org.
Now that we have our environment configured, we can download Ext JS. Ext JS has some different license flavors: commercial and open source. For this book, we are going to use the open source one. You can download the open source version at http://www.sencha.com/products/extjs/details. Scroll until the end of the page and select OPEN SOURCE GPL LICENSING, as demonstrated in the following screenshot:
We also need to download and install Sencha Cmd from http://www.sencha.com/products/sencha-cmd/download. Sencha Cmd is responsible for creating the application and making, building, and compiling Sass and Compass to generate the application's CSS. After the installation of Sencha Cmd, the
sencha command will be available from the terminal application as well.
While developing with Ext JS, we will consult the documentation a lot. Whenever we mention the name of an Ext JS component in this book, it is recommended that you go to the documentation and take a look at it. The Ext JS documentation is available at http://docs.sencha.com/extjs/5.0/. It contains guides (it is also highly recommended that you spend some time reading the guides before diving into this book since the guides provide basic knowledge about the framework), and links to blog posts and also to the documentation itself. As we will consult it a lot, we recommend installing the documentation locally as well. To do so, go to http://docs.sencha.com/, open the Sencha Guides menu, and select the offline docs link as demonstrated in the following screenshot:
A video tutorial with step-by-step instructions to set up the environment for Ext JS is available at http://youtu.be/B43bEnFBRRc.
You can use any IDE or editor of your preference to develop with Ext JS. There are a few editors that are very popular: Sublime Text, Atom, Eclipse (if you are a Java developer), Netbeans, and Visual Studio (if you are a C# developer), Notepad++, and WebStorm, among others.
If you are looking for the autocompleting feature, you can use the Sencha Eclipse Plugin that is part of Sencha Complete (paid) at http://www.sencha.com/products/complete/) or you can use WebStorm (also paid) at https://www.jetbrains.com/webstorm/).
There is also Sencha Architect (which also has the autocompleting feature). It is a what you see is what you get (WYSIWYG) editor and is a great Sencha tool that can be used with the IDE of your preference (to develop the server-side code of the application).
Feel free to use the editor or IDE you are most comfortable with to develop the source code of this book!
In this chapter, we quickly overviewed Ext JS and provided some references that are useful to read to gather the basic knowledge required to understand the terms and components we will be using in this book.
In the next chapter, we will present the application we are going to work with throughout this book, and we are also going to create it using Sencha Cmd.