| Developer(s) | Dojo Foundation |
|---|---|
| Stable release | 1.7 / December 1, 2011 |
| Written in | JavaScript |
| Operating system | Cross-platform |
| Type | JavaScript toolkit (or library) |
| License | The modified BSD license or the Academic Free License (≥ 2.1) |
| Website | http://dojotoolkit.org |
Dojo Toolkit is an open source modular JavaScript library (or more specifically JavaScript toolkit) designed to ease the rapid development of cross-platform, JavaScript/Ajax-based applications and web sites. It was started by Alex Russell, Dylan Schiemann, David Schontzler, and others in 2004 and is dual-licensed under the modified BSD license or the Academic Free License (≥ 2.1). The Dojo Foundation is a non-profit organization[1] designed to promote the adoption of the toolkit.
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Dojo widgets are components — comprising JavaScript code, HTML markup, and CSS style declarations — that provide cross-browser, interactive features:
Skins can be used to change the look and feel of Dojo widgets that are used on a page.[2]
One important feature of Ajax applications is asynchronous communication of the browser with the server: information is exchanged and the page's presentation is updated without a need for reloading the whole page. Traditionally, this is done with the JavaScript object XMLHttpRequest. Dojo provides an abstracted wrapper (dojo.xhr) around various web browsers' implementations of XMLHttpRequest, and dojo.io also supports other transports (such as hidden IFrames) and a variety of data formats. Using this approach, it is easy to have the data a user enters into a form sent to the server "behind the scenes"; the server can then reply with some JavaScript code that updates the presentation of the page.
Dojo provides a packaging system to facilitate modular development of functionality in individual packages and sub-packages; the base Dojo "bootstrap" script initializes a set of hierarchical package namespaces -- "io", "event", etc. -- under a root "dojo" namespace. After initialization of the root namespace any Dojo package can be loaded (via XMLHttpRequest or other similar transport) by using utility functions supplied in the bootstrap. It is also possible to initialize additional namespaces within or parallel to the "dojo" namespace, allowing extensions of Dojo or the development of private Dojo-managed namespaces for third-party libraries and applications.
Dojo packages can consist of multiple files, and can specify which files constitute the entire package. Any package or file can also specify a dependency on other packages or files; when the package is loaded, any dependencies it specifies will also be loaded.
Workarounds for cross-domain loading of most Dojo packages are provided (though this requires a specialized build of Dojo).
Dojo also provides a mechanism for building "profiles"; the build system takes as input a list of packages, and uses Rhino to create a single compressed JavaScript file containing those packages and all their dependencies. This allows all necessary code to be loaded and initialized at once, and permits caching of the code (most web browsers do not cache files loaded via XMLHttpRequest). Pre-built profiles for some common use cases are available for download from the same location as the full toolkit.
In addition to providing support functions for reading and writing cookies, Dojo also provides a local, client-side storage abstraction named Dojo Storage. Dojo Storage allows web applications to store data on the client-side, persistently and securely and with a user's permission. It works across existing web browsers, including Internet Explorer, Firefox, and Safari. When included in a web page, Dojo Storage determines the best method for persistently storing information. On Firefox 2, it uses native browser persistence; on other browsers it uses a hidden Flash applet. With Flash 6+ being installed on about 95% of computers connected to the web,[3] this makes the storage mechanism accessible for much of the web's installed base. For a web application that is being loaded from the file system (i.e. from a file:// URL), Dojo Storage will transparently use XPCOM on Firefox and ActiveX on Internet Explorer to persist information. The programmer using Dojo Storage is abstracted from the storage mechanism used and is presented with a simple hash table abstraction, with methods such as put() and get(). Dojo Storage is not supported in versions later than the 1.3 release.
As of January 2007, Dojo includes the following example server-side datastore implementations in the dojo.data namespace[4]:
Dojo can be used in JavaScript-based Adobe AIR applications. It has been modified to meet AIR's security requirements.
Sitepen, a Dojo consulting company, has made an Adobe AIR application called "Dojo Toolbox" using Dojo. It includes an API viewer, and a GUI to Dojo's build system. Normally, the build system is run from within Rhino, but in this AIR application the build system can be run from AIR, without use of java.[5]
The documentation for Dojo is of varying quality, with much information scattered between reference documentation, API documentation and tutorial-style documentation pages, and many of the reference documentation pages on the official site being blank apart from text such as "TODO: how to use the component/class/method"[6].
Although Dojo offers many "off the shelf" components that might be useful for a developer, some argue that it lacks flexibility or requires excessive overhead.
Dojo development can be done with any suitable editor. Some examples are Netbeans IDE, Eclipse IDE, Aptana IDE, and Komodo. Netbeans and Eclipse are Free software while there are community-versions of both Aptana and Komodo. Dojo-Plugins are available for many IDEs. For WYSIWYG development using Dojo, one can use the open source WaveMaker Visual Ajax Studio or Maqetta (HTML5 visual page editor from the dojofoundation), which also supports Team Reviewing.
In 2006, both IBM[7] and Sun Microsystems[8] have announced official support for Dojo, including code contributions.
Zend Technologies, the company behind the PHP core, has announced a partnership with Dojo, to incorporate it into the Zend Framework[9]
The Dojo Foundation is a 501(c)(6) non-profit organization founded to help open source projects. Its primary goals are to aid in adoption by companies, and encourage projects in the foundation to collaborate with one another[1].
Its sponsors and members are:
The Dojo Foundation also helps the following projects, in inclusion to the Dojo Toolkit:
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