Number validate regex

Question

From jquery.validate.js, this regex is used to validate a number. The problem is that it fails on .33 and passes on 0.33. I need to make it pass with, or without, the leading 0.

^-?(?:\d+|\d{1,3}(?:,\d{3})+)(?:\.\d+)?$

Answer 1

Try this

^-?(?:\d+|\d{1,3}(?:,\d{3})+)?(?:\.\d+)?$

The extra question mark (spot it!) will make all the part before the decimal point optional.