title: asp: access html element inside repeateritem itemtemplate from codebehind
body: <p>How to access HTML "input type="checkbox" data-item="myItems" id="id123"" in ascx.cs file when the input is in asp:repeater ?
  This does not work, cuz findcontrol only works with system.web.ui.control:</p>
  
  <pre><code>var checkBox = (System.Web.UI.HtmlControls.HtmlInputCheckBox)e.Item.FindControl("id123");
  </code></pre>
  
  <p><br>
  <br></p>
  
  <p>This:</p>
  
  <pre><code>var checkBox = (Checkbox)e.Item.FindControl("id123");
  </code></pre>
  
  <p>will work if I make asp:checkbox instead html input. <br>
  But then another question: What is  the equivalent for html input "data-" attribute in asp:checkbox ?</p>