On Tue, Nov 20, 2012 at 4:54 PM, Peter van der Zee <[email protected]> wrote:
> On Tue, Nov 20, 2012 at 10:31 PM, Rick Waldron <[email protected]> > wrote: > > On Tue, Nov 20, 2012 at 2:45 PM, Tab Atkins Jr. <[email protected]> > > wrote: > >> > >> On Mon, Nov 19, 2012 at 9:46 PM, Brendan Eich <[email protected]> > wrote: > >> > Tab Atkins Jr. wrote: > >> >> If we did this, the only reason to continue subclassing Map is to get > >> >> instanceof checks to work. Is this acceptable? > >> > > >> > I think it's either irrelevant (no one tests 'aUrlQuery instanceof > Map') > >> > or else a potential problem (cross-frame instanceof). > >> > >> People *do* perform those checks, though. For example, in a method > >> that accepts either an array or other things, a quick "foo instanceof > >> Array" check is a clear, easy way to check what you've got. > > > > > > Be careful there, it's incredibly rare to see code that does that—which > is > > I don't agree. I see often see instanceof, both with Array and with > other objects. This danger you and everybody speaks of only applies to > cross-frame scripts. Please don't lump me in, I said: 'instanceof is generally viewed (whether correctly or not) as "broken".' I said _nothing_ about cross-frame-anything. > And while this danger is real (and I don't mean > to make it sound like it isn't), I think you should first consider the > amount of people actually doing cross frame scripting because it's not > something most people touch frequently, if at all. Any studies to get > such numbers? > I'm more concerned with this: [] instanceof Object; // true Rick > - peter >
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