How do you open a file from a default location? Or a file browser?

@Thomas_Calvin  I'm not expert on this question but since no-one else has answered yet I'll add some info. This script snippet shows a possibility. However, I have a suspicion that different Illustrator installations might have different path structures. Perhaps your script could try all the path structures that you know of. Here is one that works on my system (Illustrator 29.5, MacOS 15.4.1).

- Mark

/**
 * Example of providing access to one of the Illustrator presets folders.
 * 
 * There may be better ways to do this, and I suspect that
 * this may not work on all versions and OSes.
 * 
 * @author m1b
 * @version 2025-04-29
 * @discussion https://community.adobe.com/t5/illustrator-discussions/how-do-you-open-a-file-from-a-default-location-or-a-file-browser/m-p/15293796
 */
(function () {

    // this *might* be the path to the Presets folder
    var presetsFolder = Folder(app.path + '/Presets.localized/' + app.locale);

    if (!presetsFolder.exists)
        return alert('Could not determine presets folder at "' + decodeURI(presetsFolder) + '".');

    // ask use to choose a symbol libary document
    var f = File.openDialog('Choose a symbol library', presetsFolder + '/Symbols');

    if (f)
        app.open(f);

})();