Checking for time - validation

Question

I have a form field which may have a date and may have a time in it. I need to confirm that both a date and time are present.
<input type="text" name="transdate" ... />
I can use isDate(form.transdate) to check if there is a date, but it does not check if there is a time. I wish there was a isTime() function.
Addendum
The date time fields can be made to have
These fields are concatinated via
date_cat = "#form.trans_date# #form.trans_date_h#:#form.trans_date_m# #form.trans_date_t#";
When I run this code:
cat: #date_cat# isValid(date): #isValid('date', date_cat)# isValid(time): #isValid('time', date_cat)#
I get
cat: 12/05/2018 :24 PM isValid(date): YES isValid(time): YES

Answer 1

Some people hate regular expressions. I love them. Why not just check the concatenated string?
dtRegEx = "^(0[1-9]|1[0-2])/(0[1-9]|[1-2][0-9]|3[0-1])/[1-9][0-9]{3} (0[0-9]|1[0-2]):[0-5][0-9] (am|pm)$";
if (reFind(dtRegEx, date_cat) and isDate(date_cat)) {
// valid datetime
} else {
// invalid datetime
}
RegEx Breakdown
^
string has to start with the whole pattern
(0[1-9]|1[0-2])
month in range from 01 to 09 or 10 to 12
/
date delimiter
(0[1-9]|[1-2][0-9]|3[0-1])
day in range from 01 to 09, 10 to 29 or 30 to 31
/
date delimiter
[1-9][0-9]{3}
year in range from 1000 to 9999
space
space, literally
(0[0-9]|1[0-2])
hour in range from 00 to 09 or 10 to 12
:
time delimiter
[0-5][0-9]
seconds in range from 00 to 59
space
space, again
(am|pm)
the meridiem stuff you guys from US and UK like so much :P
$
string has to end with the whole pattern
Note that the above pattern could still have you end up with invalid day ranges like 02/31/2018, that's why you should still check with isDate().

Answer 2

Here is how I addressed it, I validated the fields before the concatenation
if (form.trans_date_h == "" || form.trans_date_m == "" || form.trans_date_t == "") {
// error handling here
Then did the concatenation
date_cat = "#form.trans_date# #form.trans_date_h#:#form.trans_date_m# #form.trans_date_t#";