How can I specify optional characters in a regular expression?

Question

I have this regular expression.

MMM D[,] YYYY   
/^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\ (\d{2})\, (\d{4})$/

How i can do this [,] is optional?

MMM D, YYYY
MMM D YYYY

Answer 1

just do ,? that makes the comma optional.