by Ben Nadel
The HashKeyCopier is a utility class for use in AngularJS applications. It is designed to copy the proprietary $$hashKey from one rendered object to another as a means to cut down on the amount of DOM rendering and Directive execution that the AngularJS framework needs to carry out.
This is specifically for use in situations in which locally cached data needs to be overridden by live data returned from a remote server. When AngularJS renders data in the document body, it uses an "expando" property, "$$hashKey," to match an existing DOM node with an existing JavaScript object. It uses this key to know when it needs to re-build a DOM node; or, when it simply needs to update the content of an existing DOM node.
NOTE: I packaged this as its own module. I did this because I am not sure what the best practices are for distributing AngularJS classes. So, I went with a module that has only one injectable. More likely, I would just copy the one definition into my own app and rename it (as necessary).