Test page 3

  <script type="text/javascript">
  function foo() { alert("foo"); }
  window.onload = function() { foo(); }
  </script>

  <script type="text/javascript">
  function bar() { alert("bar"); }
  var prev_onload = window.onload;
  window.onload = function() { prev_onload(); bar(); }
  </script>