How do I truncate username and pass it to the iFrame src tag in HTML macro?

[Paras]

Users login in Confluence have an username format firstname.lastname@domain.com. I want to truncate the username to firstname.lastname and pass that value to the iFrame src tag.

How can I do that? Thanking you in advance.

[David at David Simpson Apps]

That looks like a hard ask. 

You could create a user macro to do that. 

 - Get the username

- split on @ character

- build an iframe with the username prefix in the iframe arc attribute