Exprot PDF/X-4:2008 with Illustrator settings

var myName = "myPDF";
var myFile = new File("~/Desktop/" + myName);
var myPDF = new PDFSaveOptions();
myPDF.pDFPreset = "[PDF/X-4:2008]";
app.activeDocument.saveAs(myFile, myPDF);
// app.activeDocument.close();

You can change the name of the file in line 1, the location the file is saved to (presetnly the desktop) in line 2, or the name of the preset in line 4. Uncomment (remove // from) line 6 to close the doc after it is saved.