This from Eric at Geospatial Training… Each chapter from my e-book, "The GIS Geeks Guide to Mastering the ArcGIS Server API for JavaScript” has been posted online for viewing.
The book is based on materials drawn from our Building Custom ArcGIS Server Applications with JavaScript course and covers how to use the ArcGIS Server API for JavaScript to build high performance, attractive Web mapping applications using the lightweight, browser based ArcGIS Server API for JavaScript.
Here’s Chapter 1 – Chapter 1: Introduction to ArcGIS Server
The chapters are free to everyone in pdf format.
See Also http://www.geospatialtraining.com