Write plist file with JavaScript for Automation and Objective-C Bridge.

WriteToPlist.js

// use Foundation.framework
ObjC.import('Foundation');

// get applicaiton
app = Application.currentApplication();
// use StandardAdditions
app.includeStandardAdditions = true;

array = [1, 2, 3];
array.push(['a', 'b', 'c']);
dict = {'key1': array};
dict['key2'] = 'abc';
dict['key3'] = {'x': 1, 'y': 2, 'z': 3};

// convert into Objective-C (NSDictionary)
object = ObjC.wrap(dict);

// open save dialog
options = {
  defaultName: 'Untitled.plist',
  defaultLocation:app.pathTo('desktop')
};
filePath = app.chooseFileName(options);

// write to file (Objective-C)
object.writeToFileAtomically(filePath.toString(), true);