regular expressions: match x times OR y times

Question

Lets say I need to match a pattern if it appears 3 or 6 times in a row. The closest I can get is something like \\d{3,6} but that doesn\'t quite do what I need.

\'12

Answer 1

For this case we can get away with this crafty method:

Clean Implementation

/(\d{3}){1,2}/
/(?:\d{3}){1,2}/

How?!

This works because we're looking for multiples of three that are consecutive in this case.

Note: There's no reason to capture the group for this case so I add the ?: non capture group flag to the capture group.

This is similar to paxdiablo implementation, but slightly cleaner.

Matching Hex

I was doing something similar for matching on basic hex colors since they could be 3 or 6 in length. This allowed me to keep my hex color checker's matching DRY'd up ie:

/^0x(?:[\da-f]{3}){1,2}$/i