observable

Description:

observable

Support for detecting and being notified when an object is mutated.
An observable is a way to be notified of a continuous stream of events over time.
Some suggested uses for this library:

Observe objects for changes, and log when a change occurs
Optimize for observable collections in your own APIs and libraries instead of diffing
Implement simple data-binding by listening to streams

You may want to look at the former TC39 proposal Observe.observe, which was deprecated.
Usage #
There are two general ways to detect changes:

Listen to Observable.changes and be notified when an object changes
Use Differ.diff to determine changes between two objects