Question

I am looking for some help on creating a regular expression that would work with a unique input in our system. We already have some logic in our keypress event that will only allow digits, and will allow the letter A and the letter M. Now I need to come up with a RegEx that can match the input during the onblur event to ensure the format is correct.

I have some examples below of what would be valid. The letter A represents an age, so it is always followed by up to 3 digits. The letter M can only occur at the end of the string.

Valid Input

1-M
10-M
100-M
5-7
5-20
5-100
10-20
10-100
A5-7
A10-7
A100-7
A10-20
A5-A7
A10-A20
A10-A100
A100-A102

Invalid Input

a-a
a45
4

Answer 1

This matches all of the samples.

/A?\d{1,3}-A?\d{0,3}M?/

Not sure if 10-A10M should or shouldn’t be legal or even if M can appear with numbers. If it M is only there without numbers:

/A?\d{1,3}-(A?\d{1,3}|M)/