Question

I’m new to RegEx and JavaScript and I was wondering if anyone knew what the RegEx would be for detecting whether or not an input field contained the following type of format:

• At least one alphanumeric tag which can contain spaces (e.g. “Test Tag” but not “Test@Tag”)

• Each tag separated by a single comma (e.g. “Cars, Vehicle, Large Dog, Bed” but not “Cars, Vehicle, Tiger)

An example of what I mean is this, these would be valid tags:

boy, man,girl, woman,tyrannosaurus rex, lion

And these would be invalid tags:

hat, cat, rat, c3po, @gmail

Because there are invalid characters in “@gmail”.

It should also be able to accept just a single tag, as long as the characters are alphanumeric.

Answer 1

Assuming you want to allow _ and not allow whitespace at the beginning or the end this would be the shortest solution:

/^\w(\s*,?\s*\w)*$/

Introducing whitespace at the ends:

/^\s*\w(\s*,?\s*\w)*\s*$/

Removing _ from the allowed characters:

/^\s*[a-z0-9](\s*,?\s*[a-z0-9])*\s*$/

---

This is the brute-force regex I initially posted. It translates your requirements to regex syntax. I would like to leave it here for reference.

/^\s*([a-z0-9]+(\s[a-z0-9]+)*)(\s*,\s*([a-z0-9]+(\s[a-z0-9]+)*))*\s*$/