Javascript multiple email regexp validation

Normally validation of simple email is:

/^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/

This will validate email like test@test.com

But how to validate if email is multiple?

entry 1: test@test.com, test1@test.com, test2@test.com
entry 2: test@test.com , test1@test.com , test2@test.com
entry 3: test@test.com, test1@test.com , test2@test.com
entry 4: test@test.com

This emails is a possible entries that user will input. Also expect thier is 2 or 3 or 4 or more emails sometimes.

Thanks for the answers.