You are correct. I was thinking of Object.observe which was preached as the next big thing in JS only to finally be pulled from Chrome (around version 50 IIRC)

You are correct. I was thinking of Object.observe which was preached as the next big thing in JS only to finally be pulled from Chrome (around version 50 IIRC). That said, does a native observable actually buy that much performance-wise? If not, then perhaps an addon library is better. Once a library makes it into JS, it is there forever. That's a big risk when decent libraries already exist.