An Application Programming Interface (API) defines the operations, formats, and data structures available from a networked service. The developer writes code using the API to tell a server to accomplish a task. An API is built on top of an existing programming language, and uses the syntax and features of the language to make communications with a computer easier to code.

At one point, ESRI had three web-based APIs to communicate with ArcGIS Server: Flash, Silverlight, and JavaScript. With the rise of the mobile web and improvements in browsers, the ArcGIS JavaScript API won as the browser of choice. To make the best use of the ArcGIS Server map features, it's best to learn what's available from the JavaScript API. We're going to take a tour through the API, to become familiar with what it has to offer.

Unlike the other chapters in this book, this chapter provides more of a reference than a programming exercise. Short code snippets have been added to show how...