title: change form target based on dropdown selection
body: <p>I want every dropdown option to have a target of "_blank" except option 4.  How do I switch the target based on the option selected in the form?</p>
  
  <pre><code>    &lt;form action="mypage.php" method="post" target="_blank" /&gt;
  &lt;input type="hidden" name="turnaround" value="20"&gt;
  &lt;table&gt;
      &lt;tr&gt;
          &lt;td&gt;Platform&lt;/td&gt;
          &lt;td&gt;
              &lt;select required id="cu" name="plat" style="min-width: 120px;"&gt;
                  &lt;option value="1"&gt;1&lt;/option&gt;
                  &lt;option value="2"&gt;2 (Desktop Only)&lt;/option&gt;
                  &lt;option value="3"&gt;3 (Mobile Only)&lt;/option&gt;
                  &lt;option value="4"&gt;4 (Wildcard)&lt;/option&gt;
                  &lt;option value="5"&gt;Catch-All&lt;/option&gt;        
              &lt;/select&gt;
          &lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
          &lt;td colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
      &lt;/tr&gt;
  &lt;/table&gt;
  &lt;div&gt;&lt;input type="submit" value="Select Platform" /&gt;&lt;/div&gt;
  &lt;/form&gt;
  </code></pre>