Methods and apparatus, including computer program products, implementing techniques for document object model caching and validation. A client identifies a change of a user interface (UI) element that references a node of the DOM hierarchy. The client determines whether the change of the UI element can be applied to the DOM hierarchy by using an update function, for example, a delta renderer. If so, the client finds in the DOM hierarchy the node that is referenced by the UI element and modifies at least one attribute related to the node according to the change by using the update function. Otherwise, the client sets a dirty flag.