Asp. Net Program Generation Verification Code explanation

/// <Summary>
/// The pop-up Prompt window.
/// </Summary>
/// <Param name = "mssage"> information to be prompted. </Param>
/// <Param name = "p"> reference of the current webpage. </Param>
 
Public static void Alert (System. Web. UI. Page p, string mssage)
{
String msg;
Msg = "<script language = javascript> ";
Msg = "alert (" mssage ");";
Msg = "</script> ";
P. RegisterStartupScript ("alert", msg );
}
 
/// <Summary>
/// Focus the control.
/// </Summary>
/// <Param name = "p"> reference of the current webpage. </Param>
/// <Param name = "Control_ID"> the path of the control to focus on the webpage. </Param>
/// <Example> GetFocus (this, "TextBox1") </example>
 
Public static void GetFocus (System. Web. UI. Page p, string Control_ID)
{
String msg;
Msg = "<script language = javascript> ";
Msg = "document. getElementById (" Control_ID "). focus ();";
Msg = "</script> ";
P. RegisterStartupScript ("getFocus", msg );
}