# Windows Script File

A Windows Script File (WSF) is a file type used by the Microsoft Windows Script Host. It allows mixing the scripting languages JScript and VBScript within a single file, or other scripting languages such as Perl, Object REXX, Python, or Kixtart if installed by the user. These types of scripts may also be used to link many other external scripts together using a src parameter on the <script> tag in a manner similar to HTML. Windows Script Files have the extension ".WSF". A WSF makes reference to each script module in a very basic XML hierarchy as shown below, adhering to those standards outside the <script> tags. Literal use of "</script>" or "<script>" inside your <script> tags and similar challenges can be handled by the use of CDATA, as shown within the examples.

## Error isolation

A WSF may be useful for isolating errors. Its modular nature prevents one script reference from interfering with another. Here is a WSF example with one module that produces an error and one that does not:
The first script module will produce a "divide by zero" error. Typically this would cause the script to end in the Windows Script Host but this modular method allows the script to continue and execute the second script module.

## Mixed language support

A Windows Script File supports multiple languages, as described on the Windows Script Host reference. One of the features of this file format is that you may use more than one at once. This means you can have one scripting language use code from another scripting language. The most memorable example for long-time VBScript users is the use of Microsoft JScript to service a sort request for VBScript since it does not have a built-in sort function for an array of values. VBScript users may write their own sort method or borrow one from an existing object like an ADO (ActiveX Data Objects) Recordset or a .NET (.NET Framework) ArrayList, but the fastest way to sort an array is to use the method built into JScript. Here is a basic example of how that works:
The output looks like this, sorted by ASCII code sequence:

## Exposing constants

Another very useful feature of a WSF is that the XML wrapper can be bound to an object reference or control so you can use that object's constants instead of having to declare them. In regular VBScript and JScript files, you would be forced to declare a constant's value (outside those that are internal to the Windows Script Host) in order to use the constant. An example of this is shown below:
If your object documentation only refers to the constant's name and not the constant's value, you would have no way of knowing the value without the help of an Integrated development environment to tell you what they equate to. By using the WSF reference declaration, you can use the constants without declaring their values. The example below enumerates the values of several common constants in the ADO (ActiveX Data Objects) Recordset.
Running the above script from a file with a ".WSF" extension, such as one named "EnumerateConstantsADO.wsf", will produce the result shown below:
In addition, using the object reference to expose the constants makes writing the script more like writing in a standard programming language. In fact, the contents of the sample script, written in VBScript, will actually compile into a Visual Basic program and run the same way as long as that program uses the same reference to ADODB.