Why doesn't [01-12] range work as expected?

Question

I\'m trying to use the range pattern [01-12] in regex to match two digit mm, but this doesn\'t work as expected.

Answer 1

Use this:

0?[1-9]|1[012]

• 07: valid
• 7: valid
• 0: not match
• 00 : not match
• 13 : not match
• 21 : not match

To test a pattern as 07/2018 use this:

/^(0?[1-9]|1[012])\/([2-9][0-9]{3})$/

(Date range between 01/2000 to 12/9999 )