title: Set hidden field value from C# backend
body: <p>I want to set a hidden field value from my C# backend.</p>
  <h3>My JS code :</h3>
  <pre><code>function GetSignedMessage() {
      try {
          document.getElementById(&quot;hdnbyteToRecieve1&quot;).value = &quot;PPPP&quot;;
          document.getElementById(&quot;&lt;%=hdnbyteToRecieve.ClientID %&gt;&quot;).value = &quot;PPPP&quot;;
          //document.SignedAppletDemo_View.getpdf();
      } catch (err) {
         alert(err.message);
      }
      return true;
  }
  </code></pre>
  <p>I am calling this js function from backend code.</p>
  <h3>My C# code :</h3>
  <pre><code>ScriptManager.RegisterStartupScript(Page, GetType(), &quot;disp_confirm&quot;, &quot;GetSignedMessage();&quot;, true);
  var aa = hdnbyteToRecieve1.Value;
  </code></pre>
  <p>Somehow, the value of hidden field <code>hdnbyteToRecieve1</code> and <code>hdnbyteToRecieve</code> is coming empty.</p>