Relationship between globals, Realms, and global environment records

Boris Zbarsky bzbarsky at
Tue Nov 25 09:07:47 PST 2014

On 11/25/14, 11:45 AM, Allen Wirfs-Brock wrote:
> I'm simply trying to understand what what is meant when HTML talks about changing the global object/realm/etc.

Ah.  That part is simple.

Per current HTML spec (and the Gecko implementation) when is performed, a new Realm and global object (Window) is 
created.  The WindowProxy involved is changed to point to the new global 
object.  The new Window points to the same Document that the old Window 
pointed to.

> and how that can be reconciled with a rational language semantics such as exhibited by the function I presented.

Again per current HTML spec existing functions don't change in any way. 
  They continue to perform bareword lookups against the global that 
corresponds to their Realm.  At least that's how I interpret the spec 
and how Gecko implements it; the spec itself is not very clear on this, 
because it doesn't actually define how WindowProxy works.

In any case, that's my take on the situation.  ;)


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