@gullerya/object-observer

object-observer utility provides simple means to (deeply) observe specified object/array changes; implemented via native Proxy; changes delivered in a synchronous way

objix

A powerfull, high performance, lightweight library to injecs many usefull methods into the Object prototype to sugar many use cases working with common Javascript object.

jobserve.js

A lightweight JavaScript library that allows developers to keep track of changes to JavaScript objects and/or DOM elements.