how to pass session value to external js file

i got two pages upl.aspx and datalist.aspx

i have got iframe in upl.aspx page which loads datalist.aspx

now i am creating a session on radiobutton click whiich is inside datalist i want to pass this session value to external js file so that now i have a function Hidee() in uploo.aspx page which can show its value

HOW TO DO THIS??

here is my code for up1.aspx

<a onclick="Hidee();" style="cursor: pointer">close</a></div>

<iframe id="frame1" frameborder="0" name="frame1" src="datalist.aspx">&开发者_运维百科lt;/iframe>

this is from datalist.aspx in which i have my datalist

<td align="center" > 


                <asp:RadioButton ID="rdb" runat="server"     CssClass="radio" AutoPostBack="True" OnCheckedChanged="rdb_click" /> 


                <asp:HiddenField ID="HiddenField1" runat="server" Value = '<%#Eval("FileName")%>' /> 
                </td>
                </tr>  

here is codebehind datalist.cs

public void rdb_click(object sender, EventArgs e)
    {
        string value = "";
        for (int i = 0; i < DataList1.Items.Count; i++)
        {
            RadioButton rdb1;
            rdb1 = (RadioButton)DataList1.Items[i].FindControl("rdb");
            if (rdb1 != null)
            {
                if (rdb1.Checked)
                {
                    HiddenField hf = (HiddenField)DataList1.Items[i].FindControl("HiddenField1");
                    value = hf.Value.ToString();
                }
            }
        }
        Session["Background1"] = value;
        Label2.Text = value;

    }

and in my external javascript i have function Hidee();

function Hidee()
{
var div2 = document.getElementById( "divframe1" ); 
div2.style.display = "none";
var div3 = document.getElementById( "aa" );
div3.style.display = "block";
var session ='<%= Session["Background1"] %>';
alert("you have selected" + session);
}

If upl.aspx and datalist.aspx are part of two different ASP.NET applications (hosted on different application pools in IIS), it won't be possible to share session between them. A possible workaround would be to pass values as url parameters.

UPDATE:

You cannot use server side expressions in external javascript files. You could declare a global variable in your aspx page that will hold the value which will be used in your javascript file:

In the aspx page:

<script type="text/javascript">
    var background = '<%= Session["Background1"] %>';
</script>

and then you could use background variable in the Hidee function inside your javascript file.