Gravity Forms regex for US ZIP code - php

Question

I'm trying to set up some form validation for a Gravity Form that I've created. One of the fields that I need to validate is a US ZIP code. I want to pass ZIPs that follow the nnnnn and nnnnn-nnnn patterns. Here's my code:
if ( $field->type == 'address' ) {
$zip = rgar( $value, $field->id . '.5' );
if ( preg_match( "(^(?!0{5})(\d{5})(?!-?0{4})(|-\d{4})?$)", $zip ) && ! $field->get_input_property( '5', 'isHidden' )
) {
$result['is_valid'] = false;
$result['message'] = empty( $field->errorMessage ) ? __( 'Please enter a valid ZIP code (ie. 00000 or 00000-0000).', 'gravityforms' ) : $field->errorMessage;
} else {
$result['is_valid'] = true;
$result['message'] = '';
}
}
My form continues to fail validation and I can't figure out why. I've double checked that .5 is the correct input field number of the ZIP code. Any suggestions?
My form can be found at http://marcusjones.wpengine.com/

Answer 1

shouldn't be easier to use:
/(^\d{5}$)|(^\d{5}-\d{4}$)/
or other function fe:
function isValidPostalCode(postalCode, countryCode) {
switch (countryCode) {
case "US":
postalCodeRegex = /^([0-9]{5})(?:[-\s]*([0-9]{4}))?$/;
break;
default:
postalCodeRegex = /^(?:[A-Z0-9]+([- ]?[A-Z0-9]+)*)?$/;
}
return postalCodeRegex.test(postalCode);
}
and "if" you'll add quite simple.