If you are using UpdatePanel and you want to call a javascript function after content refresh in update panel, You can use below way to do it easily,
In Page body tag , call a function RefreshContent()
<body onload="RefreshContent()">
<script type="text/javascript">
function RefreshContent()
{
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
}
function EndRequestHandler()
{
alert("Add your logic here" );
}
</script>
If you are using Master page then assign a id to body tag and also add runat="server"
<body id="body" runat="server">
protected void Page_Load(object sender, EventArgs e)
{
//For a single specific page only, use below url check and match code
if (Request.RawUrl.ToLower().Contains("Your Page Name in Lower Case"))
{
body.Attributes.Add("onload", "RefreshContent()");
}
}