Regex: Validating US zip code

Question

I'm looking for a regex that validates the US Zip Codes and cannot contain more then 2 0's at the start:

Eg: 00979 is a valid zip code (Puerto Rico)

But I want the user to refrain from entering something like 000979 or 00012

Valid Zipcodes are: 979, 0979, 00979, 970, 907, 0907, 00970 ...

Invalid Zipcodes are: 00000, 00012, 12, ...

I've come up with

/^\d[0-9][0-9]{1,3}[1-9]([\-]\d{4})?$/

but this does not validates 979. What am I doing wrong here? I've looked at other references regarding validation US Zip codes but none of them validates trailing 0's cases..

Answer 1

You can use this regex that allows up to 2 zeroes at the start:

^(?!0{3})[0-9]{3,5}$

RegEx Demo