Extract email address from string in Javascript (Google Tag manager function)

I’m looking for a way to extract the email address from a string I have already stored in a Google Tag Manager variable. I’m new with Javascript and I tried some functions I found on the internet but they all return “undefined”

Example :

function findEmailAddresses(StrObj) {
        var separateEmailsBy = ", ";
        var email = "<none>"; // if no match, use this
        var emailsArray = StrObj.match(/([a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+)/gi);
        if (emailsArray) {
            email = "";
            for (var i = 0; i < emailsArray.length; i++) {
                if (i != 0) email += separateEmailsBy;
                email += emailsArray[i];
            }
        }
        return email;
    }

My string is : ‘ You are now logged as John Doe ([e-mail]) ’ (the incorrect caracters are linked with fontawesome library problem, fixed soon) I would like to run a JS/Tag Manager function that return only [e-mail]

The Google Tag Manager functions should not use librairies and should be a JavaScript function that returns a value using the ‘return’ statement. Thanks for you help.

Regards.

Answer

This should do the job for your String:

strObj.match( '(?<=\()[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+(?=\))' )[0];