Why JavaScript objects for data instead of Xml?
Similar to the DOM, we found that accessing Xml documents via XPath in JavaScript is slow. By comparison, creating, accessing and updating JavaScript objects is fast. Furthermore, we wanted to add support for features not found in Xml, such as reflection, type information, property validators and change notification. To add these features, we implemented JavaScript object-based DataSets. Xml DataSets using XPath may be added at some point in the future.
