var dir = './test-new-folder'; // OR var dir = 'test-new-folder';

if (!fs.existsSync(dir)) {
   fs.mkdirSync(dir, '0777', true);
}

var desktopPath = (electron.app || electron.remote.app).getPath('desktop');

var dir = desktopPath + '/test-new-folder';

if (!fs.existsSync(dir)) {
   fs.mkdirSync(dir, '0777', true);
}