Appendix B. Dojo basics
Because the ArcGIS API for JavaScript is built with the Dojo Toolkit, you should be aware of a few details about Dojo. When Esri initially released the ArcGIS API for JavaScript, the company came under scrutiny for using Dojo as the core to the API as opposed to a more popular library such as jQuery. The developers at Esri stated that their reasons for choosing Dojo were that at the time the API was developed, Dojo had better tools for working with web services, and, more important, had better support for working with graphics across a variety of browsers. You can still use jQuery or any other third-party library in your applications, but one way or another, you’ll also use Dojo.
As the Dojo Toolkit has been upgraded over the years, so has the ArcGIS API for JavaScript. When the API moved to v3.0, it began using Dojo v1.7 for its core functions, and it continues to keep up with current Dojo updates.
The Dojo Toolkit is a vast resource of modules and utilities for developing robust and scalable applications, which requires an entire book of its own to cover in detail, but you can use this appendix as a starting point for the more detailed coverage in this book. This appendix covers the Dojo loader, the Dijit lifecycle, and common Dojo modules you’ll use when building applications with the ArcGIS API for JavaScript.
For more details about Dojo and the Dijit library, visit http://dojotoolkit.org/documentation/.