I need to call a javascript function from C# code. I am getting object expected error

[vamshi2804]

//javascript function
<script language="javascript" type="text/javascript">  
       function popModal() {   
           $find('ModalPopupExtender').show();            
       }    
 
</script>  
 
//C# code
 
protected void Page_Load(object sender, EventArgs e)
{
   if (!Page.IsPostBack)
   {
      string script = "<SCRIPT LANGUAGE='JavaScript'> ";
      script += "popModal();";
      script += "</SCRIPT>";
  this.RegisterClientScriptBlock("ClientScript", script);
     }
 }
 

[Frinavale]

Well you're getting that message because JavaScript couldn't not find an element with the ID "ModalPopupExtender". You need to provide the ID of the the ModalPopupExtender to the method. You can do this using the ClientID of the ModalPopupExtender.

Like this:

protected void Page_Load(object sender, EventArgs e)
{
   if (!Page.IsPostBack)
   {
      string script = "<SCRIPT LANGUAGE='JavaScript'> ";
      script += "popModal(" + ModalPopupExtender1.ClientID + ");";
      script += "</SCRIPT>";
  this.RegisterClientScriptBlock("ClientScript", script);
     }
 }

You'll have to change your JavaScript to accept the ID of the ModalPopupExtender as a parameter...and use that with the $find method:

//javascript function
<script language="javascript" type="text/javascript">  
       function popModal(ModalPopupExtenderClientID) {   
           $find(ModalPopupExtenderClientID).show();            
       }    
 
</script> 

[vamshi2804]

@Frinavale
Thank you for your quick response.

But I still get the same error.

I tried like below also

script += "popModal('" + ModalPopupExtender1.ClientID + "');";

[Frinavale]

What exactly are you trying to do?
The ModalPopupExtender has it's own JavaScript aspect that it uses to display itself. You shouldn't be trying to find it on the page...you should be calling it's methods to display it.

-Frinny