Question

I want to make a regular expression that direct the time format is valid, the format should like this:
HH:MM

so, I create a regular expression like this:

/\b[0-2][0-9]\:[0-5][0-9]\b/

But the problems occur, the user still can input something like 29:59. Which is not a valid time. How can I solve it? Thank you.

Answer 1

Use a regex OR for the hour:

/\b([01][0-9]|2[0-3])\:[0-5][0-9]\b/

The ([01][0-9]|2[0-3]) part is saying hours can be anything 00-19 or 2 with (0-3).
A regex OR takes the form of (A|B)