Regex - testing against two different patterns

Question

I have a location search field that needs to allow either a city and state, or a zip code. I have two separate regex patterns that each work separately, but am having issues combining them.

This one is for city and state; it checks to make sure that there are at least two letters, then a comma, an optional whitespace, and exactly two more letters. Works great.

var str="abc, de";
var patt1 = /^[a-z]{2,},\s*[a-z]{2}$/i;
if(patt1.test(str)) {
    alert("true");
}
else {
    alert("false");
}

This one is for zip codes. It checks to make sure there are exactly 5 numbers. Also works.

var str="01235";
var patt1 = /[0-9]{5}/;
if(patt1.test(str)) {
    alert("true");
}
else {
    alert("false");
}

I know you can do a match for alternatives by using parentheses and the pipe symbol; I've done this in the past two validate against two different phone number formats - (xxx) xxx-xxxx or xxx-xxx-xxxx:

var pattern = /((^\([0-9]{3}\) [0-9]{3}[-]{1}[0-9]{4}$)|(^[0-9]{3}-[0-9]{3}[-]{1}[0-9]{4}$))/;

But when I try to do this with my city/state and zip checks, it doesn't work. If I enter a zip code, it correctly returns true, but any and all combos of city and state return false, even when they correctly return true when the city/state pattern is used on its own. And it seems to be ignoring the requirement for exactly 5 numbers in the second possibility; it will return false if there are less than 5, but will return true if there are more than 5. Where am I going wrong with this?

var patt1 = /((^[a-z]{2,},\s*[a-z]{2}$\i)|(^[0-9]{5}))/;

I have a fiddle here: http://jsfiddle.net/EmmyS/fHkZU/

Bergi · Accepted Answer · 2013-07-19 19:13:11Z

3

Where am I going wrong with this?
var patt1 = /((^[a-z]{2,},\s*[a-z]{2}$\i)|(^[0-9]{5}))/;

You've moved the case-insensitive-modifier into the regex (escaped with a backslash but that doesn't matter). It would try to match an i character after the string end :-)

And it seems to be ignoring the requirement for exactly 5 numbers in the second possibility; it will return false if there are less than 5, but will return true if there are more than 5.

Again you've forgotten to anchor them (at least to the end, your combination attempt even anchors them to the string start).

Corrected:

var patt1 = /(^[a-z]{2,},\s*[a-z]{2}$)|(^[0-9]{5}$)/i;
// or maybe easier:
var patt1 = /^([a-z]{2,},\s*[a-z]{2}|\d{5})$/i;

Not sure where you need the capturing groups though.

Notice that it might be easier (and cleaner code) not to combine both patterns into one horrible regex, but just to test both of them and do the logic in JS, like

var str="…";
var patt1 = /^[a-z]{2,},\s*[a-z]{2}$/i, // city and state abbreviation
    patt2 = /^\d{5}$/; // or zip code
if(patt1.test(str) || patt2.test(str)) {
    alert("true");
} else {
    alert("false");
}

edited Jul 19, 2013 at 19:13

answered Jul 19, 2013 at 19:07

Bergi

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2 Comments

EmmyS Over a year ago

Unfortunately I can't do it as a conditional in the logic; this is being used in angularjs code as an ng-pattern directive, which only accepts a single pattern string.

EmmyS Over a year ago

Thank you for the link on anchors; that helps a lot.

basher · Accepted Answer · 2013-07-19 19:14:07Z

1

I know it's not what you asked, but I would keep this as 2 separate patterns. While they work on the same textbox, they serve 2 different purposes. Makes it easier to maintain.

When you get back to this pattern in a year will you be able to confidently and quickly adjust it? You're already struggling with it.

cityStatePattern = "xxx"
zipPattern = "yyy"

vs

//check for city, state or zipcode
fieldPatterno = "xxx|yyy"

I'd go with the first option every time.

answered Jul 19, 2013 at 19:14

basher

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