regex - 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.

Answer 1

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?