DOJO Interview Questions

DOJO is a modular JavaScript library that is used for the development of cross-platform, JavaScript/Ajax-based applications. Developed by the DOJO foundation, this open-source library was first released in March 2005. The DOJO framework is licensed under the modified BSD license.

This framework has many features such as

• widgets
• asynchronous communication
• packaging system
• client & server-side data storage
• support for the Adobe Integrated Runtime.

Some of the benefits of using the DOJO framework are,

• DOJO has support for modularity and asynchronous loaders.
• The DOJO toolkit provides a class-like inheritance pattern using the dojo/declare.
• DOJO allows each component to build on a set of high-quality building blocks by providing integrated infrastructure.
• It is easy to manage large-scale UI development projects using DOJO’s package system.
• The community of DOJO is another important factor for choosing DOJO. They are an open community and are readily able to help other members.

The Dijit in the Dojo is a widget system. With this, you can build Web 2.0 GUI’s with little or no JavaScript. This widget system is layered on top of the Dojo. It can either be used declaratively or programmatically.

The DojoX can be defined as the meta-package for other packages. This contains the packages that run the gamut of the JavaScript technology.

The libraries supported in the Dojo framework is the dijit. It is a library that contains the user-interface modules for widgets and layouts.

The basic directory structure of the Dojo framework contains the following three points,

• /index.html - it is the entry point for the application.
• /app - it is the application module.
• /app/main.js - it is the main script for the app module.

Some of the limitations of using the Dojo framework are,

• The Dojo framework is only supported by a limited number of browsers.
• The Dojo codes can not be hidden in the case of commercial applications.
• The documentation of Dojo is quite narrow.
• It requires many networks.

The components that come with the Dojo Framework are the Base, Dijit, Dojox, and Util.

Base - Present at the kernel of the Dojo toolkit, Base is a tiny library wrapped up into a single JavaScript file.

Dijit - It is the Dojo widget system that is used to build the Web 2.0 GUI’s without heavily using the JavaScript.

Dojox - It is a meta-package for other packages, and sub-packages defined in the Dojo framework.

Util - It is the set of utilities that are developed to utilise with the Dojo toolkit.

Packages in Dojo are a collection of modules. It is an array of package configuration objects. Packages have some extra-features which significantly enhances module portability and ease-of-use. A package can be installed using tools like the CPM. With a package configuration, you can specify the name, location, and the main file of the package.

The Dijit framework contains a set of graphical controls called the widgets. With the widgets, you can build graphical user interfaces. There are lots of widgets available in the Dojo framework to create different graphical elements.

Some of the available widgets and its uses are,

dojox.widget.AnalogGuage - It is used to display numerical data with a variety of indicators.

dojox.widget.ColorPicker - It is an HSV colour picker.

dojox.widget.Rotator - It is a widget for rotating through child nodes using transitions.

dojox.widget.Loader - It is a small experimental Ajax activity indicator.

dojox.widget.Pager - It is used to display items in a horizontal or vertical UI.

The modules in Dojo are written in the Asynchronous Module Definition (AMD) format and are used to make the code easier to author and debug. In simple terms, a module is a value that can be accessed by a single reference. It is used for modularizing the code that is splitting it up into logical subsets for handling specific functionality. A module is stored in the file system as a single file.

Some of the Dom specific Dojo functions are,

Retrieval function - The retrieval can be easily done using the dojo/dom resource’s byId method.

Creation function - Creation of elements can be done using the dojo/dom-construct’s create method.

Placement - To place a node, you can use the domConstruct.place method.

Destruction - To remove the nodes, you can either use the domConstruct.destroy function or the domConstruct.empty function.