Reading through the documentation for powershells add-type it seems you can add JScript code to you powershell session.
Firstly is there a decent example of how this is done and secondly can you use this to validate normal javascript code (as I understand JScript is the MS implementation)
This may be a good starting point
PowerShell ABC’s – J is for JavaScript (by Joe Pruitt)
Here is a code snippet from the above article: