I would like to test a number between 1 and 100
Regex = ^[1-9]?[0-9]{1}$|^100$
Try:
^[1-9][0-9]?$|^100$
Working fiddle
EDIT: IF you want to match 00001, 00000099 try
^0*(?:[1-9][0-9]?|100)$
FIDDLE