An update on Object.observe

Adam Klein adamk at
Mon Nov 2 18:27:43 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
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