title: Change HTML attribute with jQuery
body: <p>I am using jQuery 1.4.4. and I have this source code:</p>
  
  <pre><code>&lt;div id="area1"&gt;
      &lt;ul id="testlist" data-filter="false"&gt;
  
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can I change the data-filter attribute to true in jQuery?
  I tried for example:</p>
  
  <pre><code>$('#testlist').attr("data-filter").val(true);
  </code></pre>
  
  <p>but it does not work.</p>
  
  <p>Anyone an idea?</p>
  
  <p>Best Regards.</p>