// These defaults should be changed the way it best fits your site
var _POPUP_FEATURES = 'location=0,statusbar=0,menubar=0,width=765,height=580';

function raw_popup(url, target, features) {
  // pops up a window containing url optionally named target, optionally having 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) {
  // to be used in an html event handler as in: <a href="..." onclick="link_popup(this,...)" ...
  // pops up a window grabbing the url from the event source's href
  return raw_popup(src.getAttribute('href'), src.getAttribute('target') || '_blank', features);
}

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