Emit client script blocks in page

Private Sub SetFocus (ByVal controltofocus as Control)
Dim Scriptfunction as New StringBuilder
Dim Scriptclientid as String
Scriptclientid = Controltofocus.clientid
Scriptfunction.append ("<script language= vbscript>")
Scriptfunction.append ("Form1." & Scriptclientid & ". Focus")
Scriptfunction.append ("</script>")
RegisterStartupScript ("Focus", scriptfunction.tostring ())
End Sub
Description: The String object is immutable. Each time you use one of the methods in the System.String class, you create a new string object in memory, which requires a new space to be allocated for the new object. The system overhead associated with creating a new string object can be expensive when you need to perform repeated modifications to the string. If you want to modify a string without creating a new object, you can use the System.Text.StringBuilder class. For example, when you concatenate many strings together in a loop, using the StringBuilder class can improve performance.
RegisterStartupScript: Allow ASP.net server control to emit client script blocks in Page
Like the RegisterClientScriptBlock method, this method emits the script before the <form of the Page object runat= the closing tag of the server> element. When an object that renders the page is defined when the script block is emitted, you must also include two tags for the <script> element.
By using the key identity script, multiple server control instances can request the script block without sending it to the output stream two times.
Any script block with the same key parameter value is treated as duplicates.
Note Remember to add an HTML comment tag around the script so that the script does not render when the requesting browser does not support the script.