Tracking the attribute changes

1

Hi all,
I want to introduce a (pseudocode) concept of extending Data API with ability to track data changes, similar to Rails DirtyAttributes and/or Backbone.Model. Current API introduces only get, set, has, delete functions.
One could extend current Data class with methods:

/**
 *  Returns changes of value of given attribute.
 *  @param name - name of attribute whose value changed
 *  @return Array<string> - 2 element array containing value before change and current value
 */
changes(name: string) : Array<string>
/**
 *  Returns names of all attributes which were changed.
 *  @return Array<string> - array of names of attributes where value changed
 */
changed() : Array<string>
/**
 *  Removes information about attribute changes.
 */
clean() : void
/**
 *  Listens for changes of value of given attribute. 
 *  @param name - name of attribute to listen for value changes
 *  @param function - callback function with value changes: fn(before: string, after: string)
 *  @return Array<string> - array containing value before change and current value
 */
onChange(name: string, function(before: string, after: string))

and introduce a new DirtyData Object like so:

class DirtyData {
  key: string,
  value: Array<string>
}

as a Hash of attribute name as key and value changes as value.

Here is the sample usage:

Data Object: "foo"
DirtyData Object: { "foo": ["bar", "baz"] }

data.onChange("foo", (before, after) => {
  console.log("foo changed", before, after)
})
data.get("foo") -> "bar"
data.set("foo", "baz")
// log: "foo changed", "bar", "baz"
data.get("foo") -> "baz"
data.changed() -> ["foo"]
data.changes("foo") -> ["bar", "baz"]
data.clean()
data.changed() -> []

What do You think of such approach? Such PR can be pulled to core?
I think that it could be implemented using MutationObserver and/or MutationRecord.
Above approach would only apply to state of data in controller’s element.