Javascript Regular Expression to match 5 or 9 digit zipcode

Question

I have a similar issue as my recent post but with a zip code validator, I am trying to convert over to a javascript validation process. my script looks like so:

Answer 1

Change your regex to:

new RegExp("^\\d{5}(-\\d{4})?$")

Answer 2

Add anchors: new RegExp("^\\d{5}(-\\d{4})?$"). This forces the regular expression engine to only accept a match, if it begins at the first character of the string (^) and ends at the end of the string ($) being matched.

Note, that there might be a typo in the regular expression you hav given in your question: the second \d is missing a backslash.