New full Unicode for ES6 idea

Brendan Eich brendan at
Sun Feb 19 15:11:38 PST 2012

Brendan Eich wrote:
> Mark S. Miller wrote:
>> On Sun, Feb 19, 2012 at 12:33 AM, Brendan Eich <brendan at 
>> <mailto:brendan at>> wrote:
>> [...]
>>     Why the global object? Because for many VMs, each global has its
>>     own heap or sub-heap ("compartment"), and all references outside
>>     that heap are to local proxies that copy from, or in the case of
>>     immutable data, reference the remote heap.
>> [...]
>> Is this true for same origin iframes? I have always assumed that 
>> mixing heaps between same origin iframes results in unmediated direct 
>> object-to-object access. If these are already mediated, what was the 
>> issue that drove us to that?
> Not all engines mediate cross-same-origin-window accesses.

Sorry, I misused "mediate" incorrectly here to mean heap/compartment 
isolation. All engines in browsers that conform to HTML5 must mediate 
cross-frame Window (global object) accesses via WindowProxy, as 
discussed in other followups.

> I hear IE9+ may, indeed rumor is it remotes to another process 
> sometimes (breaking run-to-completion a bit; something we should 
> explore breaking in the future for window=vat).

(Hope that parenthetical aside has you charged up -- we need a fresh 
thread on that topic, though... ;-)


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