Regular expression for validating month

Question

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 expression:

1, 00, 13 and up.

Answer 1

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

Answer 2

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

Answer 3

我认为这是一个更好的，它接受'05'，但也接受'5'作为一个月：

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

Answer 4

这会奏效

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