You can read more about the dirty count in the Softimage KB article Scripting – Understanding the dirty count parameter.

This example JScript uses the dirty count to determine whether or not the current scene has been saved.

function IsSceneSaved()
{
	var dirtycount = Dictionary.GetObject( "Project.dirtycount" ).Value;
	var models = FindObjects( null, "{0496EAB0-0ECF-11d1-ABF1-00A02485CECB}" )
	 
	oEnum = new Enumerator( models ) ;
	for (;!oEnum.atEnd();oEnum.moveNext() )
	{
		var model = oEnum.item() ;
		dirtycount += Dictionary.GetObject( model.FullName + ".dirty_count" ).Value
	}

	LogMessage( dirtycount );
	return( dirtycount );
}
LogMessage( IsSceneSaved() == 0 ? "Scene is clean" : "Scene is dirty" );

In the XSI SDK, when a method or command returns an array, it returns a safe array.
So, in JScript, you have to use VBArray.toArray() to convert the safe array to a JScript array.

When you go in the other direction, and pass in an array, the XSI SDK automatically converts the JScript array to a safe array. That’s good, because you can’t build safe arrays in JScript, or convert JScript arrays to safe arrays.

Unfortunately for me, a customer came across a case where PPGItem.SetAttribute wouldn’t work with a JScript. Sure, it was with an undocumented attribute, but still…

I knew the JScript attribute was the problem because I could set the attribute in VBScript, but not JScript.

So I came up with a hack to get a safe array in JScript. I used ExecuteScriptCode to call a VBScript function that returned a safe array, which I could then pass to SetAttribute.

var s = "function a( val )\n" + 
	"a = Array( val )\n" +
	"end function";

var sa = Application.ExecuteScriptCode( 
			s, "VBScript", "a", val );

Another way to get a safe array in JScript is to use the Scripting.Dictionary. The Items method returns a safe array:

d = new ActiveXObject("Scripting.Dictionary"); 
d.Add( 0, val )
var sa = d.Items();

The docs say that XSIUtils.Environment gets system environment variables, but I think it is more accurate to say that it returns env vars of the XSI.exe process.

WScript.Shell is another way to get at the environment variables. The WshShell object’s Environment property is a collection of environment variables. For example, this snippet shows how to create a WScript.Shell object, and then check the value of the TEMP environment variable. Note that XSI.exe creates its own folder under the location pointed to by the User TEMP environment variable.

// Get WshShell object.
var oWshShell = new ActiveXObject ("WScript.Shell");

var oEnv = oWshShell.Environment("Process");
LogMessage( oEnv("TEMP") );

// INFO : C:\Users\blairs\AppData\Local\Temp\XSI_Temp_17480

var oEnv = oWshShell.Environment("User");
LogMessage( oEnv("TEMP") );
LogMessage( oWshShell.ExpandEnvironmentStrings("%USERPROFILE%") );

// INFO : %USERPROFILE%\AppData\Local\Temp
// INFO : C:\Users\blairs

You can also loop over the collection:

var oEnv = oWshShell.Environment("System");
logenv( oEnv );

function logenv( o )
{
	oEnum = new Enumerator( o ) ;
	for (;!oEnum.atEnd();oEnum.moveNext() )
	{
		var oSelItem = oEnum.item() ;
		LogMessage( oSelItem  );
	}
}