Switch supports a couple of scripting languages (JavaScript, VBScript) as explained in the Scripting reference.
In general, use JavaScript unless there is a good reason to select an operating system scripting language (like VBScript). JavaScript scripts are cross-platform, that is, they work without change on both Mac OS X and Microsoft Windows, and most of the Switch scripting examples available on the web or from other users will be in JavaScript.
At the same time, JavaScript scripts have limited "external access". For example, there is no way to communicate with interactive applications and there is no access to operating system services. If these features are necessary, on Microsoft Windows, use VBScript. To use these features on Mac OS X, the recommended way is to write JavaScript that uses the 'osascript' utility. This utility can execute dynamically generated AppleScript scripts to perform platform-specific tasks that cannot be performed in a different way.
If a script package contains more than one script program, Switch selects one of the programs for execution by looking for them in this order:
The operating system scripting language for the platform on which Switch is running (that is, VBScript).
JavaScript.
If neither of these are included, the script package cannot be executed.