ECMA plans to sign-off on ES6 in December 2014: https://mail.mozilla.org/pipermail/es-discuss/2013-November/...

But browsers are already rolling out some ES6 features now: http://kangax.github.io/es5-compat-table/es6/

"For ES6, 2014 should be a year of cleanup and minor refinement."

A whole year. I'm not gonna pretend that I have any idea how this process works. Still, what kind of a cleanup takes a year? Cities recovered from natural disasters much faster.

ES6 is going to be awesome, but the advatange I see in Dart is its optional typing system and included libraries.