title: how to handle Dropdownlist SelectedIndexchanged event in ASP.Net MVC
body: <pre><code>!{Html.TextBox("registerDetails.OtherCompanyActivity", registerModel.EditForm.OtherCompanyActivity, new { @class = "further_info", @tabindex = "15" })}
  </code></pre>
  
  <p>this is my dropdownlist. And when i have selected a value in the dropdownlist , the textbox should be made readonly.</p>