Regular Expression to Check for Minutes:Seconds (XX:XX) Format

I wish I knew more about Regular Expressions. I'm slowly learning and discovering how frickin' all mighty and powerful they are. Here's an example.

I have a field in my app where I need to make sure that users enter a time-like format, but not an actual time. I want them to enter how long in minutes and seconds it took them to do something. And I don't want to use two separate form fields.

Therefore, they might enter 36:15, which is 36 minutes, 15 seconds... obviously not a real time-of-day.

If you need to verify an actual time-of-day, just look at my previous post about using the ColdFusion IsDate() function to validate time. But if you need to do what I'm doing, check out this RegEx I created. I'm still new at RegEx, so there might be an even better way to do this.

This does exactly what I need it to do. And it will even accommodate really slow users who enter something like 114:38. But any other format will generate a message that they entered their info in the wrong format.

What's going on?

1) The carat "^" tells the RegEx to start at the beginning of the string. There it looks for any single number [0-9].

2) Next, we tell it to do this at least 1 time and not more than 3 times {1,3}.

3) Then we have a literal character ":" which is an actual character to look for.

4) Then we check for exactly 2 more numbers.

5) The "$" locks the end of the string after those two numbers have been found.