var _POPUP_FEATURES = 'location=0,statusbar=0,menubar=0,width=800,height=600';

function isUndefined(v) {
    var undef;
    return v===undef;
}

function raw_popup(url, target, features) {
  if (isUndefined(features)) {
    features = _POPUP_FEATURES;
  }
  if (isUndefined(target)) {
    target = '_blank';
  }
  var theWindow =
    window.open(url, target, features);
  theWindow.focus();
  return theWindow;
}

function link_popup(src, features) {
  return raw_popup(src.getAttribute('href'), src.getAttribute('target') || '_blank', features);
}