IsDate ArrayFormula

Question

Have just noticed isDate does not work in arrayformula.

Case

Want to filter all values if dates:

Used the formula:

=FILTER(data,ISDATE(data))

Expected result:

8/28/2018

Got:

#N/A

Question

1. Why? Other checks work in filter (isNumber, isText, isErr).
2. Workarounds?

Answer 1

1. Do not know the reason, still curious.

2. Workaround: =FILTER(data,IFERROR(DATEVALUE(data))) was found here

Note: Workaround will NOT work for dates formatted as:

dd.mm.yyyy

You may use a duck-typed workaround:

=FILTER(data,REGEXMATCH(MID(data,7,4),"20\d{2}"))

Will check if formatted date has a 20XX year string inside.