How do I match a specific pattern and exclude specific sub-strings with regex

Question

How do I match a specific pattern and exclude specific sub-strings with regex case insensitive

I am trying to write Regex for New Zealand address validation. This is the valid character set which I want to capture case insensitive which includes A to Z numbers and letters hyphen "-" and forward slash "/" as well as Maori accented characters for Maori vowels ā, ē, ī, ō, ū and works.

....

var regex = /^[\/A-zĀ-ū0-9\s\,\''\-]*$/;

....

It needs to exclude the following sub-strings case insensitive, with or without spaces to be valid

PO Box

Private Bag

(tricky as both those sub-strings could include spaces or not and be upper or lower case depending on how the user types them)

and the string must start with a number to be valid

e.g.

This is invalid:

Flat 1 311 Point Chevalier Road, Point Chevalier, Auckland 1022, New Zealand

This is valid:

1/311 Point Chevalier Road, Point Chevalier, Auckland 1022, New Zealand

311/1 or 311-1 or 1-311 are all considered valid by NZ Postal Service.

example if this if statement is true considering the regex above then the address string is invalid:

// Allowed character set
var regex = /^[\/A-zĀ-ū0-9\s\,\''\-]*$/;

// Get the address string and convert to lowercase for evaluation pseudocode
var str = getValue().toLowerCase();

// Strip spaces 
str = str.replace(/\s/g, '');

// If the sub string "pobox" or sub string "privatebag" or string doesn't start with a number or doesn't match allowed character set address is invalid
if(str.includes("pobox") || str.includes("privatebag") || (str.match(/^\d/) == null) || (!regex.test(str))){

....

Thanks I really appreciate the input of the community and I know there are Regex gurus out there. I am trying to simplify this so I can use HTML5 form validation rather than a clunky JavaScript evaluation.

To require a digit as first chracter: ^\d ... for disallowing some condition at certain points in your pattern eg a neg. lookahead can be used. Together maybe something like this demo. — bobble bubble
– bobble bubble, Commented Aug 25, 2022 at 10:30

Arnold Daniels · Accepted Answer · 2022-08-25 15:34:37Z

2

One option is to first match the expressions you want to exclude and then regex with the allowed character set.

/^.*(po\s*box|private\s*bag).*$|^\d[\/a-zĀ-ū0-9\s\,\'\-]*$/i

By capturing the excluded patterns, you can check if group 1 has a value. If so, you know that the string should be skipped

var regex = /^.*(po\s*box|private\s*bag).*$|^\d[\/a-zĀ-ū0-9\s\,\'\-]*$/i;
var match = str.match(regex);

if (match && !match[1]) {
   // valid address
} else {
   // invalid address
}

See https://regex101.com/r/AiL6Dy/2

edited Aug 25, 2022 at 15:34

answered Aug 24, 2022 at 22:55

Arnold Daniels

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4 Comments

Jeremy Leys Over a year ago

that is just awesome and works for every scenario except one requirement which is the string must start with a number. If I can tweak it to include that requirement it is perfect. e.g. jsfiddle.net/jeremy_tactical/ad71ey6k/4

Jeremy Leys Over a year ago

Hi Arnold, I am still a real noob when it comes to regex, how do I also check if the string starts with a number combined with your beautiful regex you wrote, I attempted var regex = /^.*(po\s*box|private\s*bag).*$|^\d|^[\/a-zĀ-ū0-9\s\,\'\-]+$/i; obviously wrong though.

Arnold Daniels Over a year ago

@JeremyLeys I've updated regex. Now it says, start with a number followed by zero or more valid chars. If you want the number followed by 1 or more valid chars, use + instead of *. Basically, that part is just regular regexp. Use regex101 to play around with it. It also shows an explanation.

Jeremy Leys Over a year ago

Arnold thank you this is a brilliant solution, you are awesome.

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