Regex Bugging Out (retrieve user domain after @ before TLD)

[spamushere]

I am trying to retrieve the domain of my site users in order to assign them specific organisation based privileges.

If their email address is email@example.com, I want to extract example. If it’s email@ex.ample.com I want to extract ex.ample

The regex I have is (?<=@)[^.].[^.](?=.)

But I’m struggling to integrate this into the code. My code as follows:

$w.onReady(async function () {
 let userEmail = await memberData.loginEmail;
    retrieveTeamFromEmail(userEmail);
    $w('#userAccountSetupIntroText').text = ("Let's set up your account. We have your company as " +
        userEmail + ".\n\nTell us a little more about yourself.");
})

function retrieveTeamFromEmail(userEmail) {
 return userEmail
        .replace(?<=@)[^.]*.[^.]*(?=\.);
}

I’m getting an error at .replace:

What am I doing wrong?

[spamushere]

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