Regular expression for validating month

What is the regular expression for validating a month with the leading zero?

Passes regular expression:

01,02,03,04,05,06,07,08,09,10,11,12

Fails regular expre开发者_JAVA技巧ssion:

1, 00, 13 and up.

/^(0[1-9]|1[0-2])$/

/^01|02|03|04|05|06|07|08|09|10|11|12$/

I think this is a better one, it accepts '05', but also '5' as a month:

/(^0?[1-9]$)|(^1[0-2]$)/

this will work

/(0[1-9])|(1[012])/