page must open in new tab after passing parameters

function Show(strl,strp,strn)
    {
    debugger;
    var l=strl;
      var p=strp;
      var n=strn;
      var Geturl='http://'+strl+':'+strp+'/'+strn;
  
    OpenWin= window.open(Geturl,"_blank");
     
    }
 
THIS IS MY JAVASCRIPT IAM PASSING 3 PARAMETERS FROM BUTTON CLICK  FROM ASPX.CS
protected void Button1_Click(object sender, EventArgs e)
    {
string strl = "localhost";
            string strp = "81";
            string strn = "trendademo";

            Button1.Attributes.Add("onclick", "Show('" + ...