Regular expression for a list of items separated by comma or by comma and a space

Question

Hey, I can't figure out how to write a regular expression for my website, I would like to let the user input a list of items (tags) separated by comma or by comma and a space, for example "apple, pie,applepie". Would it be possible to have such regexp? Thanks!

EDIT: I would like a regexp for javascript in order to check the input before the user submits a form.

Almost any language has simple `string.split` operations for that, what language do you use for this? Easy to combine with a `string.replace` or a `string.trim`. — Caspar Kleijne, Feb 15 '11 at 09:05
What have you tried so far? Have you tried JavaScript `string.split(',')` method? — Michał Niklas, Feb 15 '11 at 09:08
I would do it with a "split by regular expression" if you have this possibility, like this `string.split(new RegExp('([ ]*[\,][ ]*)+'))` — Lukasz, May 31 '15 at 12:06

Bennor McCarthy · Accepted Answer · 2011-02-15T09:17:33.413

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What you're looking for is deceptively easy:

[^,]+

This will give you every comma-separated token, and will exclude empty tokens (if the user enters "a,,b" you will only get 'a' and 'b'), BUT it will break if they enter "a, ,b".

If you want to strip the spaces from either side properly (and exclude whitespace only elements), then it gets a tiny bit more complicated:

[^,\s][^\,]*[^,\s]*

However, as has been mentioned in some of the comments, why do you need a regex where a simple split and trim will do the trick?

edited Feb 15 '11 at 09:17

answered Feb 15 '11 at 09:09

Bennor McCarthy

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I just need to check that in javascript, then I will do the explode / trim trick in PHP to get out the array of items :) thanks anyway! – Masiar Feb 15 '11 at 09:18
By the way, in javascript would this do the trick: new RegExp(/[^,]+/); ? – Masiar Feb 15 '11 at 09:22
It should do, but you should be able to simplify it to `"apple, pie,applepie".match(/[^,]+/g);` Have a look here: http://jsfiddle.net/SD6Bt/ – Bennor McCarthy Feb 15 '11 at 09:29
The 'g' is necessary to tell it to match as many times as it can. – Bennor McCarthy Feb 15 '11 at 09:30
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The more complicated solution is not trimming the ending space: https://jsfiddle.net/2k9or1b7/2/ – techguy2000 Dec 21 '17 at 00:32
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I do not think this is correct. Try "cat, dog , ant( elephant , lion(tiger)), bird" input and one element will be "elephant ". So the spaces after the match are not skipped. – user3742309 Jan 20 '20 at 12:43

score 5 · Answer 2 · answered Dec 02 '12 at 16:20

5

Assuming the words in your list may be letters from a to z and you allow, but do not require, a space after the comma separators, your reg exp would be [a-z]+(,\s*[a-z]+)*

This is match "ab" or "ab, de", but not "ab ,dc"

answered Dec 02 '12 at 16:20

David

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This requires repeating the pattern (two times `[a-z]`) – Danon Nov 24 '17 at 08:44
The result of `http://www.example.com'.match(/[a-z]+(,\s*[a-z]+)*/g)`: `["https", "www", "example", "com"]` – jiminikiz Aug 05 '21 at 21:36

score 3 · Answer 3 · answered Jan 30 '17 at 13:58

3

Here's a simpler solution:

    console.log("test, , test".match(/[^,(?! )]+/g));

It doesn't break on empty properties and strips spaces before and after properties.

answered Jan 30 '17 at 13:58

DerpyNerd

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ah yes the all too underappreciated negative lookahead – Dash Winterson Apr 26 '20 at 21:20
If it ain't broken ;) – DerpyNerd Apr 28 '20 at 08:16

score 3 · Answer 4 · answered Jan 17 '18 at 21:52

This thread is almost 7 years old and was last active 5 months ago, but I wanted to achieve the same results as OP and after reading this thread, came across a nifty solution that seems to work well

.match(/[^,\s?]+/g)

Here's an image with some example code of how I'm using it and how it's working

Regarding the regular expression... I suppose a more accurate statement would be to say "target anything that IS NOT a comma followed by any (optional) amount of white space" ?

score 3 · Answer 5 · edited Aug 24 '20 at 14:11

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I often work with coma separated pattern, and for me, this works :

((^|[,])pattern)+

where "pattern" is the single element regexp

edited Aug 24 '20 at 14:11

peeebeee

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answered Aug 24 '20 at 11:29

Seb

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I like the idea for complex pattern you don't want to repeat: `^(?!,)((^|, ?)pattern)+$` allows to check for a coma or coma space separated list of `pattern`. This should be equivalent to `^pattern(, ?pattern)*` – tbussmann Sep 11 '20 at 13:10

score 2 · Answer 6 · answered Feb 15 '11 at 09:05

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This might work:

([^,]*)(, ?([^,]*))*

answered Feb 15 '11 at 09:05

Ted Hopp

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You should anchor this, otherwise it will always match any string since the entire expression is optional. – Tim Pietzcker Feb 15 '11 at 09:28

score 0 · Answer 7 · answered Jul 27 '17 at 14:39

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([^,]*)

Look For Commas within a given string, followed by separating these. in regards to the whitespace? cant you just use commas? remove whitespace?

answered Jul 27 '17 at 14:39

luis santos

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score 0 · Answer 8 · edited Mar 25 '22 at 09:04

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I needed an strict validation for a comma separated input alphabetic characters, no spaces. I end up using this one is case anyone needed:

/^[a-z]+(,[a-z]+)*$/

Or, to support lower- and uppercase words:

/^[A-Za-z]+(?:,[A-Za-z]+)*$/

In case one need to allow whitespace between words:

/^[A-Za-z]+(?:\s*,\s*[A-Za-z]+)*$/
/^[A-Za-z]+(?:,\s*[A-Za-z]+)*$/

edited Mar 25 '22 at 09:04

Wiktor Stribiżew

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answered May 26 '21 at 15:34

Filgaia

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score -1 · Answer 9 · edited Jul 15 '22 at 10:14

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You can try this, it worked for me:

/.+?[\|$]/g

or

/[^\|?]+/g

but replace '|' for the one you need. Also, don't forget about shielding.

edited Jul 15 '22 at 10:14

user815129

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answered Jul 13 '22 at 11:06

Kiril Harlinskyi

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score -10 · Answer 10 · answered Feb 15 '11 at 09:07

-10

something like this should work: ((apple|pie|applepie),\s?)*

answered Feb 15 '11 at 09:07

kusma

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Regular expression for a list of items separated by comma or by comma and a space

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