For alphanumeric tags separated by commas?

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 and nothing else, no spaces. (e.g. "Cars,Vehicle,Tiger Cactus, Bed")

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

boy,man,girl,woman,tyran开发者_StackOverflow社区nosaurus rex,lion

And these would be invalid tags:

hat, cat, rat, c3po, @gmail

Because there are spaces between the tags and invalid characters.

Also, how would I count the tags for imposing a limit?

Edited for clarification!

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(?:([\w\s]+)(?:,\s*))* would get any number of tags separated by commas.

(?:([\w\s]+)(?:,\s*)){n} would match n tags where n is an integer.

(?:([\w\s]+)(?:,\s*)){0,n} would match 0 to n tags where n is an integer.

In order to count the tags, you'll need to check the number of captured groups.