Is there a javascript equivalent to VB's "LIKE #"?

Question

I need to write a function that can detect whether a string input is a valid format for a date. Allowable formats are:

#### (e.g. 2003)
##/#### (e.g. 12/2003)
#/#### (e.g. 9/2003)
##/####-##/#### (e.g. 12/2003-04/2005)

But I need to prevent invalid strings (e.g. "20031", "ABCD", "200A").

I've written a function to do this in VB already (below), but I need to do it in Javascript.

VB

Public Sub detectDateFormat(ByVal myDate As String)
    If myDate Like "####" Then
        'Do Stuff 1
    ElseIf myDate Like "##/####" Or myDate Like "#/####" Then
        'Do Stuff 2
    ElseIf myDate Like "##/####-##/####" Then
        'Do Stuff 3
    Else
        'Invalid date format
        Exit sub
    End If
End Function

It seems javascript has no equivalent to "Like", and it's tricky to detect if a character is a number or letter. Can anyone suggest a good way to do this?

score 6 · Accepted Answer · edited Mar 30 '19 at 13:25

6

Closest you'll get is probably regular expressions. Much more powerful than LIKE but also can be more complicated.

For example:

If myDate Like "####" Then

Would be:

if (/^\d{4}$/.test(myDate)) { ... }

edited Mar 30 '19 at 13:25

Donald Duck

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answered Nov 16 '12 at 11:36

Lloyd

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You can also use isNaN(value), which detects invalid numbers.. so `if(isNaN(2003A)){ return "valid number required"}`. – Jarede Nov 16 '12 at 11:38
3

Yes and no. The problem with that is he is checking for 4 digits specifically. So with isNaN 123456789 would be just as valid as 2012. – Lloyd Nov 16 '12 at 11:39
Yep you're right. regex is the best for what he's doing but worth keeping in mind isNAN – Jarede Nov 16 '12 at 11:40
1

Prefer `isFinite` over `isNaN`, [less double negative confusion](http://www.refactoring.com/catalog/removeDoubleNegative.html) :P – Esailija Nov 16 '12 at 11:41
@Lloyd Thank you. This looks like just what I'm after. What about the more complicated formats of ##/#### and ##/####-##/####? Can they be handled the same way? – Urbycoz Nov 16 '12 at 11:42
1

Yes. `\d{2}\/\d{4}-\d{2}\/\d{4}` etc. – Lloyd Nov 16 '12 at 11:43
1

@Lloyd you'll need to escape those `/`s – Paul S. Nov 16 '12 at 11:43
Yeh always forget to do that :P – Lloyd Nov 16 '12 at 11:44
@Lloyd. Thanks. I owe you my salary for today :-) – Urbycoz Nov 16 '12 at 13:17

Is there a javascript equivalent to VB's "LIKE #"?

1 Answers1