title: jquery bind button click event fails
body: <p>test.html:</p>
  
  <pre><code> &lt;html&gt; 
       &lt;head&gt;
          &lt;script type="text/javascript" src="jquery-1.4.2.js"&gt;&lt;/script&gt;
          &lt;script type="text/javascript" src="test.js"&gt;&lt;/script&gt;
       &lt;/head&gt;
       &lt;body&gt;
          &lt;input id="but2" type="button" value="2"/&gt;
       &lt;/body&gt;
   &lt;/html&gt;
  </code></pre>
  
  <p>jquery-1.4.2.js is downloaded from <a href="http://jquery.com/" rel="nofollow noreferrer">http://jquery.com/</a></p>
  
  <p>test.js:</p>
  
  <pre><code>var fn=function(){
    alert('success!');
  };
  
  $('#but2').click(fn);
  </code></pre>
  
  <p>When clicked the button, nothing happened. I debugged for very long time but didn't find the root cause. Please help.</p>