image processing 100+ images to be below 600KB but above 500KB

/*
https://mindfulretouch.com/the-course/saving/saving-quality/
*/

var doc = app.activeDocument;
var filename = doc.name;
var foldername = doc.path.name;
var filepath = doc.path;
var parentfilepath = doc.path.parent
var jpegQuality = 70; // desired quality
var maxfilesize = 512000; // max size in bytes
var dec = 5; // decreasing step
var minimumqual = 50; //minumum desired quality
savefolder = new Folder(filepath + '/BATCH/');
savefolder.create();
saveFile = new File(savefolder + '/' + filename.split('.').slice(0, -1).join('.') + ".jpg");
doc.flatten();
doc.pathItems.removeAll();
doc.channels.removeAll();

function savebatchweb(saveFile, jpegQuality) {
    var sfwOptions = new ExportOptionsSaveForWeb();
    sfwOptions.format = SaveDocumentType.JPEG;
    sfwOptions.includeProfile = true;
    sfwOptions.interlaced = 0;
    sfwOptions.optimized = true;
    sfwOptions.quality = jpegQuality;
    doc.exportDocument(saveFile, ExportType.SAVEFORWEB, sfwOptions);
}
savebatchweb(saveFile, jpegQuality);
while (saveFile.length > maxfilesize) {
    jpegQuality = jpegQuality – dec;
    saveFile = new File(saveFile);
    saveFile.remove();
    savebatchweb(saveFile, jpegQuality);
    if (jpegQuality <= minimumqual) {
        break
    }
}
doc.close(SaveOptions.DONOTSAVECHANGES); //closes file