How can I modify the "Save as PDF" script to avoid the save dialogue?

var doc = app.activeDocument;
var pdfOption = 'PDFX3_CanDo_X3'; // Name of your PDF setting
var pdfSuff = '.pdf'; // Suffix for PDF
function getOptions (set) {
    var options = new PDFSaveOptions ();
    options.pDFPreset = set;
    return options;
    }
function saveCopyAsPDF (set, suff) {
        var original_file = doc.fullName;
        var arr = doc.name.split(".");
        var extension = "";
        if (arr.length > 1) {
            extension = "." + arr.pop()
            };
        var filename = arr.join(".");
        var destFolder = null;
            destFolder = activeDocument.path
        var options = this.getOptions (set);
        var targetFile;    
            targetFile = this.getTargetFile (filename, suff, destFolder);
            doc.saveAs (targetFile, options);
        doc.close ();
        app.open (File (original_file));
        }
function getTargetFile (docName, ext, destFolder) {
    var newName = "";
        newName = docName + ext;
    var myFile = new File (destFolder + '/' + newName);
    return myFile;
}
saveCopyAsPDF (pdfOption, pdfSuff);

You will have to modify at least the second line and insert the name of your own pdf export settings. The script saves a PDF of your active document in the same folder as the original AI. After that it closes the PDF and re-opens the original AI file.