How to pop up a javascript warning prompt before turning the page

mrqinmo

As long as the page is turned, the script will not prompt
I am using
Response.Write("<script>alert('alert')</script>");
Response.Redirect("aa.aspx");

xueh366

Response.Write("<script>alert('alert')</script>");
Response.Write("<script>window.location='http://163.com';</script>);

wild_kid

Response.Write("<script>alert('Warning');window.location='aa.aspx';</script>);

snowyc

Response.Write("<script>alert('Welcome to Mumushu's Home');location.href='http://mumushu.haokoo.net(or xx.aspx)';</script>");