Returns the path of the currently running script:

// File: path.w_js (JScript)
var exe  = Window.EngineFullName
var w_js = Window.ScriptName

   var shell=new ActiveXObject("WScript.Shell");
       shell.Popup(exe + "\n" + w_js,0,"Path",16);

   Window.Close(); 

'VBScript
exe  = Window.EngineFullName
w_js = Window.ScriptName

Dim shell
Set shell=CreateObject("WScript.Shell")
    shell.Popup exe & vbCr & w_js,0,"Path",16

Window.Close

Notes:

1. Run its (double click), Window.ScriptName == Full Path
2. Run its (from command line: engine.exe path.w_js): Window.ScriptName == Offset Path