Does this actually work, though? I would expect it to fail similarly as this fails (note, may hang your browser or a tab, depending on your browser):

  var foo = [0];

  function setFoo() {
    console.log("Callback");
    foo[0] = 1;
  }

  setTimeout(setFoo, 100);
  console.log("Waiting..");
  while (!foo[0]);
  console.log("Done.");

Edited the original message with reversed arguments to setTimeout; doesn't seem to affect the results though. Really need to love the complete lack of error messages though..