JavaScript RegEx validation: how to highlight what didn't match

Hello, all,

I'm in the process of writing something to add to an existing project.  The ability for a user to include up to five email addresses to CC an attachment to said addresses.  I've got the validation working as I want it.  Now, just for giggles, I'd like to have the ability to highlight what part of a malformed email address didn't match the email mask.

I've seen examples where, in a string search, the entered word would be highlighted in other words.  For example:  A list of words like, "car", "escape", "abracadabra", and someone enters "ca", then it would appear like:

car

escape

abracadabra

But I wonder if RegEx can be used to highlight what failed validation of an email address?

V/r,

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