Class Options is designed as static class. Typically there is no need to create more that one instance of this class per a game. The usage is straightforward:

function initSFX() {
    Options.load();                         // load options from a file
    if (Options.musics)                     // access option 'musics'
        SFXManager.playBackgroundMusic();
}
   
// ... or ... function toggleMusics()
{
    Options.musics = !Options.musics;       // toggle 'musics' option
    Options.save();                         // save options to a file } 

As I mentioned before, Options class is static. All its fields are saved/loaded to/from a file by static function save() and load(). The file is JSON formatted and it is placed under the root application's directory ("data://settings.dat"). To store/load all static fields an iterator is used:

// iterate all object fields for (var prop in obj)
    console << prop << "\n";
   
// iterate all class fields
for (var prop in MyClass)
    console << prop << "\n";

The iterator returns all fields including functions, so new "pure" object instance is created. The object instance has only valid fields:

// create pure object without functions (pure object) var options =  {};
for (var opt in Options)
    if (typeof Options[opt] != #function)   // skip functions
        options[opt] = Options[opt]         // create new attribute with value

Here is full implementation:

// "static" class that provides basic functionality for "Options" used in 2d game development class Options
{
    // All these class variables will be serialized     var nick = "player01";     var level = 0;
    var score = 0;     var musics = false;
    var sounds = false;
   
    // ... etc, you can add/remove fields according your needs     //     // Static functions     // Static function that saves options to file (json)
    function save()
    {
        // rewrite file
        var file = Stream.openFile("data://settings.dat", "w+");
        if (!file) {
            logE("Unable to create settings file!");
            return;
        }
        // create pure object without functions (pure object)
        var options =  {};
        for (var opt in Options)
            if (typeof Options[opt] != #function)   // skip functions
                options[opt] = Options[opt]         // create new attribute with value
        file.printf("%V", options);                 // formatted print to file
        file.close();                               // close and release
    }     // Static function that loads options from file (json)
    function load()
    {
        // open file for reading
        var file = Stream.openFile("data://settings.dat", "r");
        if (!file) {
            logW("Unable to load settings file!");
            return;
        }
        var options = parseData(file);              // load data to json
        file.close();                               // close file
        for (var opt in options)                    // iterate all attributes
            Options[opt] = options[opt];            // apply to class
    }     // }