title: How to disable or enable a bootstrap submit button if checked checkbox
body: <p>I need to enable or disable a bootstrap submit button on a form if a checkbox is cheched or not</p>
  
  <pre><code>echo "&lt;div class='panel panel-danger'&gt;&lt;div class='panel-heading'&gt;OBSERVACIONES&lt;/div&gt;&lt;div class='panel-body'&gt;";
  echo "&lt;div class='input-group'&gt;";
  echo "&lt;label class='checkbox-inline'&gt;&lt;input type='checkbox' name='visto' id='visto' value=''&gt; Visto bueno del Responsable&lt;/label&gt;";
  echo "&lt;/div&gt;"; 
  echo "&lt;/div&gt;"; 
  
  ...
  
  echo "&lt;input type='submit' class='btn btn-primary' value='SAVE' name='grabaperaus' formaction='update.php'&gt;";
  </code></pre>