How to "SaveAs" with filename generated from form field?

// force to non-sensative case stringvar sTestName = aDocumentFileName.toLowerCase();// split into file name and extensionvar aTestName = sTestName.split('.');// get first 4 characters of file name - length of 'test'aTestName[0] = aTestName[0].substr(0, 4);// create test document file namevar sTestDocument = aTestName.join('.');// see if test name is 'test.pdf'if (sTestDocument = 'test.pdf')

// Variables we use in the filename taken from fields somewhere in the form
var Var1 = xfa.resolveNode("form1.#subform.TextField1").rawValue;
// Directory where the form should be saved - i.e. the desktop of user 'jack'
var FixPath = "/C/Users/Jack/Desktop/";
 
// This functions checks the current file name. If it is not the correct file name we don't save the file under a new file name
if (event.target.documentFileName === "MyForm.pdf") 
	{
	// Concatenate the variables to a file name
	var NewFileName = "MySavedForm_";
	NewFileName += Var1;
	NewFileName += ".pdf";
	// Replace all characters that are not allowed to be used in a save path – this it to avoid an raise error
	NewFileName = NewFileName.replace(/[\s\!\?\<\>\'\"\*\/\\\=\?\^\`\{\}\|\~]+/g, "_");
	// Concatenate save path with new file name for this form and show it into this field
	this.rawValue = FixPath + NewFileName; 
	}
else
	{
	this.rawValue = event.target.path;
	}

if (event.target.documentFileName === "MyForm.pdf")
		{
		//A variable for the Folder Level Script
		SaveAsTarget = xfa.resolveNode("form1.#pageSet.Page1.TargetInformation").rawValue;	
		try
			{
			event.target.LCB_SaveAs(event.target);
 
			// Show message to inform the user, where the new file was saved.
			xfa.host.messageBox("File has beed saved under:\r\r" + SaveAsTarget, "File Saved", 3, 0);
			xfa.form.execInitialize();
			}
		catch(e)
			{
			xfa.host.messageBox(e.toString().replace("RaiseError: ","") + "\r\rEnsure the destination folder exists and there isn't already a file with the same file name in that folder!", "Failed to save file", 0, 0);			}
		}
else
		{
		// Open the 'Save As' dialog to let the user choose the target and filename.
		app.execMenuItem("SaveAs");
		}

this.path;