jQuery's focus() gets triggered again on a blur()
<p>Say I have an input field "lastname", but I don't want people to insert something if the "firstname" field is still empty. Example: <a href="http://jsfiddle.net/GQyHp/" rel="nofollow">http://jsfiddle.net/GQyHp/</a></p>

<p><pre><code>$('input[name=lastname]').focus(function() {
  if (!$('input[name=firstname]').val()) {
    alert('First enter your first name');
    $(this).blur();
  }
});</pre></code></p>

<p>If I click the "lastname" field I get the popup, but after I click 'OK' it fires the same popup again. If I remove the <code>blur()</code> there's no second popup.</p>

<p>How can I prevent this thing from being triggered by the <code>blur()</code> function?</p>
