regex emails separated with slashes

Question

How do I make sure all the emails is separated with slashes in html pattern? Below is what I have so far. (Regex novice here)

^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[az]+[/]{1,4}$

Currently:

• abc@abc.com,abc@abc.com false
• abc@abc.com/def@def.com false
• abc@abc.com/aaa@aaa.com/ false
• abc@abc.com/ true

My goals:

• abc@abc.com,abc@abc.com false
• abc@abc.com/def@def.com true
• abc@abc.com/aaa@aaa.com/ false
• abc@abc.com/ false
• abc@abc.com true

Answer 1

Use a quantified group to allow any number (including 0) of emails followed by / at the beginning, and then a single email at the end.

^(?:[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]+\/)*[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]+$

DEMO

If you only want to allow 1-4 emails, change the * to {0,3} . This is only 0-3 because it only counts the 3 emails with / after them, not the email at the end.

To limit the total size, you can use a lookahead at the beginning:

^(?=.{0,320}$)(?:[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]+\/)*[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]+$