A few months back I noticed an interesting interaction between how direct eval
is defined and multiple globals. What happens if, in one global, you call an
eval from another global as if it were a direct eval?
var indirect = otherGlobal.eval;
eval = indirect;
print(eval("this") === this);
print(indirect("this") === this);
Standards currently don't say what should happen here because it's multiple globals, so
what should this do? IE9 and Opera print false both times for this. Firefox prints
true, then false -- but only if the global and otherGlobal are from the same origin (so
on pages with the same scheme/host/port, more or less). If they're from different
origins (but have set document.domain to the same value) Firefox too prints false.
Chrome and Safari throw an EvalError calling another window's eval (for both
"direct" and indirect calls) without that window as |this| for the call.
The Chrome/Safari behavior would resurrect the vestigial EvalError, so I don't
think it makes sense. It also contradicts the specification of the steps in
the definition of the eval function. Firefox's behavior is inconsistent and
seems not amenable to host-agnostic specification as ECMA would require. Thus
we are left with the IE9/Opera behavior, which seems sensible and natural to
me: an eval function should always act in the context of the global from which
it came.
What needs to be done to standardize this behavior? And more generally, what
needs to be done to begin standardizing multiple globals in ECMAScript,
including issues like this one?
Jeff
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