title: Display Alert if Checkbox is unchecked and text field is not empty
body: <p>I have this form when information is being store into DB. I have a checkbox and a text field. Either one are required, but if the text field isn't empty, there's a good chance the checkbox should be checked. So I'd like to display an Alert if the Text Field has a value in it, and the checkbox isn't checked. I'd like this alert to appear when hitting the Submit button. Here's my form:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;form id="form" name="form" action=?post=yes" method "post"&gt;
     &lt;input type="checkbox" name="close" id="close" value="Yes"&gt;&lt;label for="close" title="Close this RMA"&gt;Close this RMA&lt;/label&gt;
     &lt;label&gt;&lt;input type="text" name="dateshipped" id="dateshipped"/&gt;&lt;/label&gt;
     &lt;button type="submit"&gt;Save and Continue&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>So if checkbox "close" IS NOT checked AND "dateshipped" IS NOT NULL, then display alert when click Submit.</p>
  
  <p>Thank you.</p>