How to use C++ enum in Qt .js file?

I need to create a file with several shared functions for multiple QML files.

I tried to create a .js file, but seems like C++ enums don't work here. FileSystemModel.TYPE_DIR is undefined here, while in QML it works fine after import FileSystemModel 1.0

.pragma library

.import FileSystemModel 1.0 as FileSystemModel

function fsItemTypeToImage(type) {
    console.log(FileSystemModel.TYPE_DIR)
    switch (type) {
    case FileSystemModel.TYPE_DIR:
        return "/img/dir.png"
    case FileSystemModel.TYPE_FILE:
        return "/img/file.png" 
    }
    return null
}

FileSystemModel.h:

class FileSystemModel : public QAbstractListModel {
    Q_OBJECT 
public:
    enum Roles { NameRole = Qt::UserRole + 1, SizeRole, DateRole, TypeRole };

    enum ItemType {
        TYPE_UNKNOWN = 0,
        TYPE_FILE,
        TYPE_DIR, 
    };
    Q_ENUM(ItemType)

registration in main.cpp:

qmlRegisterType<FileSystemModel>("FileSystemModel", 1, 0, "FileSystemModel");