title: Concatenate id in jQuery
body: <p>I have the following html:</p>
  
  <pre><code>&lt;div id="myDiv1_" class="formElement1"&gt;&lt;asp:TextBox ID="TextBox1" CssClass="formInput1" runat="server"&gt;&lt;/asp:TextBox&gt;&lt;/div&gt;&lt;br /&gt;
  &lt;div id="myDiv2_" class="formElement1"&gt;&lt;asp:TextBox ID="TextBox2" CssClass="formInput1" runat="server"&gt;&lt;/asp:TextBox&gt;&lt;/div&gt;&lt;br /&gt;
  &lt;div id="myDiv3_" class="formElement1"&gt;&lt;asp:TextBox ID="TextBox3" CssClass="formInput1" runat="server"&gt;&lt;/asp:TextBox&gt;&lt;/div&gt;
  </code></pre>
  
  <p>And I have the following jQuery code:</p>
  
  <pre><code>$('input[type="text"]').focus(function () {
      $(this).addClass("formElement1");
  });
  
  $('input[type="text"]').blur(function () {
      $(this).removeClass("formElement1");
  });
  </code></pre>
  
  <p>What I am trying to do is when the input box has focus I want to change class for the div.  I am trying to change the <code>$(this).addClass</code> to use something like <code>$('#' + div_id + textbox_id').addClass</code>.</p>
  
  <p>However, being somewhat new to jQuery, I am not sure how to accomplsh this.  Any help is appreciated.</p>
  
  <p>Thank you</p>