An update on Object.observe

Matthew Phillips matthew at
Mon Nov 2 19:21:36 UTC 2015

> Over three years ago, Rafael Weinstein, Erik Arvidsson, and I set out to
> design and implement what we believed to be the primitive underlying the
> data-binding system of MDV ("model-driven views"). We prototyped an
> implementation in a branch of V8, then got agreement from the V8 team to
> build a real version upstream, while pushing Object.observe ("O.o") as a
> part of the upcoming ES7 standard and working with the Polymer team to
> build their data-binding system on top of O.o.
> Three years later, the world has changed in a variety of ways. While other
> data-binding frameworks (such as Ember and Angular) showed interest, it was
> difficult to see how they could evolve their existing model to match that
> of O.o. Polymer rewrote from the ground up for its 1.0 release, and in that
> rebuilding did not utilize O.o. And React's processing model, which tries
> to avoid the mutable state inherent in data-binding systems, has become
> quite popular on the web.
> After much discussion with the parties involved, I plan to withdraw the
> Object.observe proposal from TC39 (where it currently sits at stage 2 in
> the ES spec process), and hope to remove support from V8 by the end of the
> year (the feature is used on 0.0169% of Chrome pageviews, according to
> For developers who have been experimenting with O.o and are seeking a
> transition path, consider using a polyfill such as
> or a wrapper library like
> - Adam

What is Polymer using in place of Object.observe?
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