Passing a list from one web form in the javascript of another web form

 List LineLista = new List();
        foreach (GridViewRow row in GridView1.Rows)
        {
            
            LineLista.Add(row.Cells[3].Text + " " + row.Cells[4].Text);
          }

        string LineList = string.Join(",", LineLista.ToArray());
        txtLineList.Text = LineList;
......
.....
...

protected void Button2_Click(object sender, EventArgs e)
    {
        Session["s2"] = txtLineList.Text;
        Response.Redirect("GELinija.aspx");
    }

Now I don't understand well what should I do? Where to declare the string as public and what should I do in the second web form?

I use this in the second web form:

protected void Page_Load(object sender, EventArgs e)
       {        
          
                 
           if (Session["s2"] != null)
            {
              string prom = Session["s2"] as String;
           }
    }

and then in the javascript I have: