[c#] How to select a div element in the code-behind page?

I have a div element:

<div class="tab-pane active" id="portlet_tab1">

I want to control this element from the code-behind page and remove the class "active"

NOTE:

• Div doesn't contain the runat="server" property.

• This is not the master page file but this is another file named "AssignImages.aspx" and it contains ContentPlaceHolder.

The div is inside this ContentPlaceHolder:

<asp:Content ContentPlaceHolderID="ContentPlaceHolder1" runat="server" ID="Content1">  

You have make div as server control using following code,

<div class="tab-pane active" id="portlet_tab1" runat="server">

then this div will be accessible in code behind.

@CarlosLanderas is correct depending on where you've placed the DIV control. The DIV by the way is not technically an ASP control, which is why you cannot find it directly like other controls. But the best way around this is to turn it into an ASP control.

Use asp:Panel instead. It is rendered into a <div> tag anyway...

<asp:Panel id="divSubmitted" runat="server" style="text-align:center" visible="false">
   <asp:Label ID="labSubmitted" runat="server" Text="Roll Call Submitted"></asp:Label>
</asp:Panel>

And in code behind, simply find the Panel control as per normal...

Panel DivCtl1 = (Panel)gvRollCall.FooterRow.FindControl("divSubmitted");
if (DivCtl1 != null)
    DivCtl1.Visible = true;

Please note that I've used FooterRow, as my "psuedo div" is inside the footer row of a Gridview control.

Good coding!

Give ID and attribute runat='server' as :

<div class="tab-pane active" id="portlet_tab1" runat="server">

//somecode Codebehind:

Access at code behind

    Control Test = Page.FindControl("portlet_tab1");
    Test.Style.Add("display", "none"); 

    or 

    portlet_tab1.Style.Add("display", "none"); 

id + runat="server" leads to accessible at the server

you'll need to cast it to an HtmlControl in order to access the Style property.

HtmlControl control = (HtmlControl)Page.FindControl("portlet_tab1"); control.Style.Add("display","none");