VBScript Version 2.0

by Lloyd Borrett
AVBUG Backup, March 1997

The "Active Platform" is Microsoft's strategy for bringing Internet technology into the easy reach of those seeking to implement Internet, Intranet and the next generation of client/server solutions. The strategy involves three core components: Active Desktop, Active Server and ActiveX controls.

What is VBScript?

Visual Basic Scripting Language (VBScript), a web browser scripting language based on Visual Basic, is a key part of the Active Platform. VBScript enables us to activate:

• objects defined by the Internet Explorer object model;
• intrinsic HTML objects such as those used in HTML forms;
• ActiveX controls; and
• Java applets.

VBScript syntax is based on that of Visual Basic (VB), so it is easily understood by VB programmers. Also like VB and unlike JavaScript, VBScript is case insensitive. The main difference between VB and VBScript is that a VBScript variable is almost typeless. Internally, everything is stored in the variant data type, which maintains type information and automatically converts information between types transparently to the programmer.

Microsoft Internet Explorer v3.0 shipped with version 1.0 of VBScript and JavaScript (Microsoft's Java based scripting language). Unfortunately, v1.0 of VBScript lacked important programming features such as constants and the ability to pass by reference.

VBScript and Netscape Navigator

Netscape Navigator v3.0 doesn't support VBScript, but NCompass Labs provides a plug-in that implements VBScript. Unfortunately, I haven't used this plug-in or studied how it compares to Microsoft's implementation of VBScript. If you're a Netscape Navigator fan, check it out for yourself at www.ncompasslabs.com.

VBScript Version 2.0

Microsoft has just released version 2.0 of VBScript and JScript. You can download the update for Microsoft Internet Explorer v3 from Microsoft's VBScript home page at www.microsoft.com/vbscript/.

The keywords added to VBScript v2.0 are listed in the following table:

Which VBScript Version?

As part of releasing VBScript v2.0, Microsoft is encouraging programmers who use v2.0 features to refer their users to a page where they can download the update. As usual, there's an animated logo to go with this.

It seemed a good idea to put this reminder onto the home page of the AVBUG website. It also seemed sensible to use the new Script Engine ID functions to test which version of VBScript was in use and only notify those users who had the earlier version. Hence the following VBScript code was written:

<script language="VBScript">
<!--
' Determine the version number.
Dim Version, RequiredVersion

RequiredVersion = 2
Version = ScriptEngineMajorVersion
If Version = 0 Then Version = 1

' Check if up-to-date version
If Version < RequiredVersion Then
  ' Prompt client
  document.write "This site requires you to have_
    a newer version of VBScript.<br>"
  ' Display a button that goes to the MS download page
  document.write "<a href=""http://www.microsoft.com/_
    msdownload/scripting.htm"" target=""_top"">"
  document.write "<img src=""images/vscript.gif"" width=""88"""
  document.write "height=""31"" vspace=""0"" border=""0"" alt="""">"
  document.write "<img src=""images/leave.gif"" width=""19"""
  document.write "height=""8"" border=""0""></a>"
End If
-->
</script>

The first line <script language="VBScript"> tells the web browser that you will be using VBScript. The next line <!-- effectively comments out the script to web browsers that don't understand VBScript. The rest is straight forward. Get the version number, check if it's up-to-date and write the necessary HTML script to the web page if the user should update.

The testing phase showed up something interesting. On my computer the logo wasn't displayed, which was expected as I'd already updated my Internet Explorer v3.01 to VBScript v2.0. However, on the next test system, using Internet Explorer v3.01 without the VBScript v2.0 upgrade, the logo also wasn't displayed! On a third, supposedly identical, system the logo was displayed as expected.

Further investigation revealed that the problem system thought it was using version 3 of VBScript! It seems likely that one of the many Internet Explorer, VBScript or Visual Basic related beta add-ons or updates from Microsoft is causing this.

Licensing VBScript

The VBScript interpreter can be easily added to most programs by simply including the VBScript DLL, which is an OLE server. Microsoft has made the licensing requirements for adding VBScript to your programs quite reasonable. Details can be obtained via the VBScript home page at www.microsoft.com/vbscript/.

For More Information

If you want even more details about VBScript version 2.0, download the Language Reference and Tutorial from the VBScript home page.

For more details about the ActiveX Platform, check out Microsoft's ActiveX home page at www.microsoft.com/activex/.