How to redirect to another page after alert message in c#?

There is some situation where we want to show alert message and confiration
message before redirecting to another page.

Method 1

1	Response.Write("<script> alert('Your Message.');window.location='TargetpageURL'; </script>");

Method 2

1	ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "ScriptKey", "alert('Your Message will go here.');window.location='TargetpageURL'; ", true);

Method 3

1	HTMLHelper.jsAlertAndRedirect(this, "This is an alert.", ResolveUrl("~/Default.aspx"));

Method 4

1 2 3 4

string  strScript = "<script>"+"alert('your message.');";                 strScript += "window.location='test.aspx';";                 strScript += "</script>";         Page.ClientScript.RegisterStartupScript(this.GetType(), "Startup", strScript);