title: Dynamically enable/disable SUBMIT button in twig
body: <p>Facing an issue that I could easily solve with the help of JS, but failing to do it in twig. I have a couple of fields in twig, and a submit button. I would want to validate these fields' data in frontend before actually submitting them, and have the "Submit" button disabled as long as the condition is unsatisfacatory. The problem in case:</p>
  
  <pre><code>&lt;div class="col-lg-12"&gt;
      &lt;div class="form-group field"&gt;
          &lt;label&gt;Description:&lt;/label&gt;
          &lt;textarea model="description" name="description"&gt;&lt;/textarea&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  &lt;div class="col-lg-6"&gt;
      // checking if user has forgotten to add description, to prevent data submitting
      &lt;button type="submit" class="btn btn-default blue" {% if description == "" } % disabled="disabled" {% endif %}&gt;
      Submit
      &lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>In JS or AngularJSi could easily solve this problem, but is there any means of achieving the same result in Twig? I need it to check the status of description dynamically and react accordingly.</p>
  
  <p>Already tried:</p>
  
  <ul>
  <li>min-length - does not prevent submitting, only colors the field after it is activated, does not work</li>
  </ul>
  
  <p>Is there any means to do it? Thank you in advance!</p>