This is going in circles. I cite ES6 features now implemented by all the majors, and point to bignums as a proposal pre-dating Dart and pre-dating other ES6 pr

This is going in circles. I cite ES6 features now implemented by all the majors, and point to bignums as a proposal pre-dating Dart and pre-dating other ES6 proposals that got implemented. You assert against all evidence that, unlike all the other ES6 stuff implemented, a bignums proposal that was accepted for ES6 and prototyped in V8 would have been rejected by Apple and Microsoft. Makes total sense! :-| Your goal-post shifting had the effect of letting Google off the hook for lack of uplift other than SIMD, so far. Great development tools and beneficial debugging! Lousy argument and defense against the lost opportunity for not only JS but dart2js, frankly. A VM is an incredibly expensive investment, but Lars et al. were tired of JS and wanted what they wanted when they wanted it. (So does my three-year old.) Whether it makes economic sense in 40 years (the time-frame I've heard for when Dart finally takes over)? Who can say. Unfalsifiable. That Dart has cost tens of millions of direct NRE at Google, and years of lost opportunities with V8 and TC39, is in the Basil-Fawlty-ian category of the bleeding obvious. There's no way to waffle around this point. You have to hold your breath for 40 years and hope.