title: how to get span in tr with jquery
body: <p>I have a table:</p>
  
  <pre><code>&lt;table id="myTable"&gt;
      &lt;tbody&gt;
        &lt;tr&gt;
         &lt;td&gt;&lt;span data-mydata="data1"&gt;first value data1&lt;/span&gt;&lt;/td&gt;
         &lt;td&gt;&lt;span data-mydata="data2"&gt;first value data2&lt;/span&gt;&lt;/td&gt;
        &lt;/tr&gt;
         &lt;tr&gt;
         &lt;td&gt;&lt;span data-mydata="data1"&gt;second value data1&lt;/span&gt;&lt;/td&gt;
         &lt;td&gt;&lt;span data-mydata="data2"&gt;second value data2&lt;/span&gt;&lt;/td&gt;
        &lt;/tr&gt;
     &lt;/tbody&gt;
   &lt;/table&gt;
  </code></pre>
  
  <p>I want to change the span texts at the last tr with jquery, I got all the span in the row with:</p>
  
  <pre><code>$('#myTable tbody tr:last td span')
  </code></pre>
  
  <p>what I want is the span which attr data-mydata is equal to data2.</p>
  
  <p>how can I do it?</p>