JS Delete Referral for Google Tag Manager

jsDeleteReferal.js

function deleteReferral(referrer) {

  // More info: go.zedwoo.de/deleteReferral
  // To specifically mean the dot, use \\.
  // It should start with regex: Add ^ at beginning
  // It should end with regex: Add $ at end
  // Optional character: Add ? after character

  var referrals = [
    'slashless.com$',
    'referrer1\\.com$',
    'referrer2\\.com$',
    'referrer3\\.com$',
    'referrer4\\.com$',
    '^mail\\.',
    '^deref-\\.',
    
    // only checks when it starts with it
    '^3d-?secure\\.',

    // checks anywhere in the string
    '3d-?secure\\.',
  ];
  var hname = new RegExp('https?://([^/:]+)').exec(referrer);

  if (hname) { 
    for (var i = referrals.length; i--;) {
      if (new RegExp(referrals[i]).test(hname[1])) {
        return null;
      }
    }
  }
  return referrer;
}