webpack-bootstrap-ui-kit/src/js/drivers/google.track.external.links.js

function _gaLt(event) {
  if (typeof ga !== "function") {
    return;
  }

  var el = event.srcElement || event.target;

  /* Loop up the DOM tree through parent elements if clicked element is not a link (eg: an image inside a link) */
  while (
    el &&
    (typeof el.tagName == "undefined" ||
      el.tagName.toLowerCase() != "a" ||
      !el.href)
  ) {
    el = el.parentNode;
  }

  if (el && el.href) {
    /* link */
    var link = el.href;
    if (link.indexOf(location.host) == -1 && !link.match(/^javascript:/i)) {
      /* external link */
      /* HitCallback function to either open link in either same or new window */
      var hitBack = function (link, target) {
        target ? window.open(link, target) : (window.location.href = link);
      };
      /* Is target set and not _(self|parent|top)? */
      var target =
        el.target && !el.target.match(/^_(self|parent|top)$/i)
          ? el.target
          : false;
      /* send event with callback */
      ga(
        "send",
        "event",
        "Outgoing Links",
        link,
        document.location.pathname + document.location.search,
        { hitCallback: hitBack(link, target) }
      );

      /* Prevent standard click */
      event.preventDefault ? event.preventDefault() : (event.returnValue = !1);
    }
  }
}

/* Attach the event to all clicks in the document after page has loaded */
var w = window;
w.addEventListener
  ? w.addEventListener(
    "load",
    () => {
      document.body.addEventListener("click", _gaLt, !1);
    },
    !1
  )
  : w.attachEvent &&
    w.attachEvent("onload", () => {
      document.body.attachEvent("onclick", _gaLt);
    });