Ext JS 4 is, by far, the most sophisticated JavaScript library available and provides an amazing set of widgets for almost all practical design concerns. It does everything we could possibly want in order to develop complex, cross-browser compatible applications that require a high degree of user interaction. In this chapter, we will:
- Learn about core Ext JS 4 MVC concepts
- Explore practical project design and development conventions
- Install the Ext JS 4 development framework and introduce Sencha Cmd
- Generate an Ext JS 4 application skeleton for the 3T application
Ext JS has come a long way since starting out as an extension to the Yahoo User Interface (YUI) library. Each new version has been a significant improvement on the previous one and Ext JS 4 is no exception. Those new to Ext JS will appreciate the elegant framework design and consistent API, while those transitioning from Ext JS 3 will appreciate the improvements in many areas, including the introduction of the MVC design pattern. Regardless of your background, this chapter will help you be productive with Ext JS 4.
It should be noted that Ext JS 4 is not the only JavaScript MVC framework available today. Angular.js and Backbone.js, for example, are both very capable development frameworks, with MVC features similar to Ext JS 4. They do not, however, have the extensive documentation, build tools, and commercial support that make Ext JS 4 so appropriate for enterprise application development.
Technology aside, a thoughtful and consistent application design is critical when developing enterprise applications. The quality of the application's architecture will determine the maintainability, scalability, and overall cost of the application during the project lifecycle. The benefits of a well-designed application include the following:
- The application will be easier to understand. New team members will quickly come up to speed if there is a consistent way of doing things.
- The application will be easier to maintain. Enhancements and new functionalities will be far simpler to implement if you have consistent application design guidelines.
- Code consistency. A well-designed application will have well-documented naming conventions, directory structures, and coding standards.
- The application will be multideveloper friendly. On large projects, many people will be involved and a consistent design strategy will ensure that everyone is on the same page.
Less-tangible benefits are often overlooked when you start a new project and excitedly work on the first prototype for the proof-of-concept presentation. The ability to refactor and scale a project from simple beginnings is often a key factor in enterprise application development. Regardless of how small the project may seem in the initial phases, you can be certain that business users will want to change workflows and layouts as soon as they become familiar with the application. New functionality will be requested and old functionality will be deprecated. Components will be moved and redesigned as the application evolves over time. A consistent and well-thought-out application design will make these project lifecycle processes less daunting. Thankfully, the Ext JS 4 application architecture itself encourages a formal and well-structured application design.