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27 April 2011, 13:37

"Model View Controller" for JavaScript library Ext JS 4

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Ext JS 4 Logo Version 4 of Ext JS is the most comprehensive release in the history of the JavaScript library, according to Sencha, the vendor of the library. The firm bases this assessment on revisions made to the library's architecture along with 350 new APIs, 50 new classes and completely revised documentation.

A new "Plug-in Free" Charting package removes the need of earlier versions of Ext JS to use Flash to display charts in older browsers. In Ext JS 4 it is even possible to display charts in Microsoft's outdated (but still widely used) Internet Explorer 6 (IE6) without a plug-in, thanks to the library’s new graphics engine. IE6 is one of 21  browser versions supported (Chrome 5+, Firefox 3+, IE6+, Safari 3.2+ and Opera 10+), in which the JavaScript library runs in quirks and strict modes. In more modern browsers, it supports forthcoming functions of HTML5.

Sencha has also launched support for the MVC-like (Model View Controller) pattern. MVC allows a developer to seperate the user interface (the view) from the data (the model) and orchestrate the interaction between the two (the controller). With that separation of responsibilities in place, a developer can iteratively enhance the view or model and add more application logic to the controller as needed. The approach also allows prototypes to be presented relatively quickly and then rapidly enhanced to production code. Sencha says it has introduced MVC to help standardise architecture patterns for larger development teams to make it easier for developers to "get up to speed" as they move between projects.

A new class system is intended to help developers, for example, to detect dependencies. Ext JS 4 also allows the library to run in a sandbox for the first time. Different versions of Ext JS can therefore be run on one page without colliding. Other revisions were made to the grid components, which are now modular and able to support "infinite" amounts of data without paging, and in support for themes, which now use stylesheet language Sass (syntactically awesome stylesheets) and CCS meta-framework Compass. For an overview of these and additional changes, see "What's new in Ext JS 4".

Sencha dual licenses the library under the GPLv3 or a commercial licence. The library and SDK tools can be downloaded from the Sencha site.


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