isDate() validation

[ekorn]

Hi Chris,
had some trouble with the isDate() check. I had a look at the regex and it themes like it would expect something like MM/DD/YYYY but when the regex part is successful the next part fails .
Could you have a look at it and maybe include it in your test file.

Cheers,
Nico

[foxbunny]

I just got burned by this. In my case, I don't really care about the date format, as long as it can be parsed by Date.parse(), so I do this:

var someDate = Date.parse(someDate); // This never throws
if (!isNaN(someDate)) {
    someDate = new Date(someDate); // This won't throw as long as someDate is not NaN
}

I'm not sure how robust Date.parse is, but unless you want a whole custom date parser with format strings, or depend on an existing date parser library (I'm not aware of anything except maybe Date.js), I think it's best to just let the value run through Date.parse, and make sure it's a non-NaN value.

[foxbunny]

So, I added the test that sort of addresses this problem. You can see in my next commit (b6a2950) passes the test (but is broken in other ways). I didn't do the pull request because this way of validating dates is ridiculous. First of all, it is date and time validation (you can say "11:00pm" to make it pass). The only reason it is silghtly 'better' (well, debatable, for sure) is that it doesn't enforce a date format. In all other respects, it's crap. It even passes stuff like "11" (which translates to "11pm 31st of Oct 2001", if it makes any sense).

An alternative solution is to pass format parameter using YYYY, YY, MMMM, MMM, MM, M, DD, and D wildcards. The MMMM and MM wildcards would be full month name, and short month name respectively, but then we have a locale problem.

[chriso]

Yeah isDate() was a user-contributed validator. Date validation is a nightmare - I'll have to think of the best way of moving forward with this one..

[chriso]

Actually @foxbunny I've added the changes you mentioned in this commit. Can you let me know how this goes? It (impressively) passes the tests.. (TIL about Date.parse!)

[foxbunny]

I haven't been able to find a better solution. All parsers I've looked at will parse just about anything. If you throw a cow at them, they'll parse it into a Date object. So they can't be used reliably to validate dates. I think it should be noted in the docs, that isDate() should be used only if you want to make sure it's a 'pareseable string', and that one should use regex for more strict validation.

[chriso]

I've added a note in the README, thanks