On Feb 12, 2012, at 3:02 PM, Brendan Eich wrote: > Andrew Paprocki wrote: >> On Sat, Feb 11, 2012 at 8:32 PM, Brendan Eich<[email protected]> wrote: >>> It's well-specified by 15.9.3.1 etc. >> >> I was reading http://es5.github.com/x15.9.html and I see the spec for >> allowing NaN as the "this time value". Where did the "Invalid Date" >> toString() came from? > > toString is underspeicified but it seems implementations all agree -- when > the Date instance's time value is NaN, "Invalid Date". > >> I don't see it on that page at all, yet all the >> browsers seem to return it. > > We could spec this, FWIW. Not a big deal.
now https://bugs.ecmascript.org/show_bug.cgi?id=268 >> >> I was thinking of trying it out when running in a "debug" mode to help >> catch errors. Is there any actual real use in the wild for a Date with >> a NaN value? > > Not sure. Probably, since it goes back 16 years. No one is inclined to find > out the hard way, I bet. We could add throwing as a strict mode behavior but > then we are enlarging strict mode from what it is today in shipping browsers. I would expect that this, isNaN(new Date(Date.parse(someString))) or an equivalent formulation occurs someplace on the web as a check for validity of date strings. The constructor call is not really necessary in this case but that doesn't mean that someone hasn't written code exactly like this. Allen
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