Sencha Touch Interview Questions

Sencha Touch is the leading MVC based, User Interface JavaScript library, which is built specifically for the Mobile Web. This web framework is used chiefly for building data intensive cross-platform mobile and web applications. Developers use this to develop user interfaces that look and feel like native applications on supported devices such as mobile or tablets. It is basically centered on web standards such as HTML5, CSS3 as well as JavaScript. The main goal of Sencha Touch is to assist and expedite quick and easy development of HTML5 based mobile apps, which run on iOS, Android, Windows, BlackBerry, Tizen and other devices, simultaneously allowing a native look and feel to the apps.

Sencha Touch has many important features, which makes it a powerful tool used in mobile developing apps:

• Sencha Touch comprises a set of GUI based components for use within the mobile web applications. Any user specifically optimizes these components or controls for input. This includes buttons with device specific themes and effects; sliders, selectors, and combo-boxes; a list component with momentum-scrolling and an index bar; form elements such as text fields for email, date picker, and address; toolbars and menus; a minimal icon set; bottom toolbars; movable tabs; as well as a map component which supports multi-touch gestures such as pinch and zoom.
• All the components or controls can be themed according to the target device. This is done using Sass. Sass is a style sheet language built over CSS.
• Adaptive layouts, smooth scrolling and animations improve the web application experience for the mobile user.
• Furthermore, Sencha Touch has eight inbuilt transition effects comprising slide under or over the current element, flip, pop, and cube. It supports common touch gestures built from touch events, which are web standards but are supported only by iOS, Android and some other touch enabled devices. These include tap, double tap, scroll, swipe and pinch.
• Themes that are out of the box and completely native looking, which are available for every major platform are also a key characteristic of Sencha Touch. These enable the developer to make web and hybrid applications match the look and feel of the target platforms.

Sencha Touch follows the MVC architecture. MVC is the abbreviation for Model View Controller. It is basically an architectural pattern, which separates the application into logical components such as application data, control code and view, thus making it more manageable. This separation allows large-scale apps to become flexible as well as easy to maintain.

The GNU General Public License (GPL) is the most extensively and popularly used free and open source software (FOSS) license in the world. The GPL was originally created as well as sponsored by the Free Software Foundation (FSF). It is now one of the most widely used free software license, which guarantees end users the freedom to run, study, share and modify the software.

The GPL is a copyleft license- this means that derivative work can only be distributed under the same license terms. In addition to clarifying the rules about licenses that are already compatible with the older version of GPL, GPLv3 is also newly compatible with a few other licenses such as the Apache License 2.0. Besides this, GPLv3 also affords its users more advanced defenses against patent aggression than any other free software license.

Ext JS is a pure JavaScript application framework for building interactive cross platform web applications using techniques such as DHTML, Ajax, and DOM scripting. Ext JS is abbreviation for Extended JavaScript and it can be used as a simple component framework.  It may be used to create dynamic grids on otherwise static pages as well as like a full framework for building single-page applications.

The GUI support by Sencha Touch effortlessly ascends to various resolutions for maximum compatibility with different iPhones and iPad, as well as the various Android phones. HTML5 and CSS3 allow higher flexibility. It also extends immense support for animations and enhanced touch events in the apps.

While Ext JS is a framework for building client side apps for desktop, Sencha Touch is basically a framework for building client side adds for mobile devices. One could easily compare Ext JS to Sencha Touch in a similar way as comparing Windows to Microsoft. Obviously, modern browsers on desktop, pads or phones should support Ext JS framework. However, Sencha Touch is optimized for the pads and phones. Since maximum numbers of people are known to access the mobile and web apps with their mobile devices, Sencha Touch is an important tool for all developers.

Here are some of the disadvantages:

• The APIs made with Sencha Touch do not have access to the camera, contacts and accelerometer of the device.
• Sencha Touch doesn’t provide the facility for push notification. This is a major disadvantage and due to this reason, the developers need to use web sockets or long polling.
• Concurring with the general public license policy, Sencha Touch is a free for open source applications, even though it is paid for the commercial applications.
• Sencha Touch is also not the best option for hardcore graphics as well as animation apps like the gaming apps.

The new Sencha Touch Audio Video feature offers HTML5 to deliver components like audio and video, and a local Storage proxy for saving data offline. Moreover, it comes with CSS3 style sheets for robust styling layer possible. It also provides a simple Container for HTML5 Video.

Distribution of a Sencha Touch application via a general-purpose browser, irrespective of which device is used, is free of charge and an embedded license is not required. A general-purpose web browser has a URL bar and a general browser as Chrome.