KageDB.open abstraction fragment

gistfile1.js

        var onsuccess;
        Object.defineProperty(req, "onsuccess", {
            get: function () {
                return onsuccess;
            },
            set: function (onsuccess_internal) {
                req.removeEventListener('success', onsuccess);
                onsuccess = function onsuccess(event) {
                    var db = event.target.result;
                    db.kage_kageDB = self;
                    helper.bindListeners(db, self, ["abort", "error"]);
                    try {
                        if (typeof version === 'number' && db.setVersion && db.version < version) {
                            db.setVersion(version);
                            if (self.onupgradeneeded) {
                                self.onupgradeneede(event);
                            }
                        }
                        onsuccess_internal.call(this, event);
                    } catch (e) {
                        if (self._autoClose) {
                            db.close();
                        }
                        throw e;
                    }
                    if (self._autoClose) {
                        db.close();
                    }
                };
                req.addEventListener('success', onsuccess);
            }
        });