Response.Write("<script>alert('"+str+"');</script>");
-----------------------------------------
Response.Write("<script language='javascript'>");
Response.Write(" alert('"+str+"');");
Response.Write("</script>");
-----------------------------------------
Response.Write("<script language='javascript'>");
Response.Write(" alert(\""+ str+"\");");
Response.Write("</script>");
---------------------------------------
Page.RegisterClientScriptBlock("check","<script language=javascript>"+salert+"</script>");
-------------------------------------------------
Page.RegisterClientScriptBlock("check","<script language=javascript>"+salert+"</script>");
----------------------------------------------------
Response.Write("<script>alert('"+str.Replace("'","\\'")+"');</script>");