title: Can not set vissability on DIV element to true manually. "TH:IF" issue
body: <p>I have the following DIV:</p>
  
  <pre><code>.. &lt;div class="row" th:if="${error}" id="divError" name="divError"&gt;
        &lt;div class="col-lg-12"&gt;
              &lt;div class="alert alert-danger" role="alert" th:text="${error}" id="errorMessenge"&gt;An
                  error occured&lt;/div&gt;
        &lt;/div&gt;
     &lt;/div&gt; ...
  </code></pre>
  
  <p>Now I have the following SCRIPT:</p>
  
  <pre><code>function someFunction(){
  .........................
     if(something){
        $("#errorMessenge").text("Error for example"); // &lt;- works 
        //HERE I WANT TO SET THIS "TH:IF" ON ROW "divError" TO TRUE
        //SO THE ROW WITH THE "Error for example" WILL SHOW.
     }
  }
  </code></pre>
  
  <p>I tried things like:</p>
  
  <pre><code>$("#divError").css("display", "");
  $("#divError").css('visibility', 'visible');
  $("#divError").css('display','block');
  $("#divError").show();
  </code></pre>
  
  <p>Nothing works.
  My question is: Is that div hidden or does not exists ? Because if it does not exists there is no point for me to trying make it "visible" and if that is so how can I work through it manually. When  ${error} attribute is added to the Module in the java controller it works just fine but when I want to set it on the fly it does not work.</p>