I have found a solution for my problem.
Since in JavaScript .0 and ['0'] are the same things I made the following workaround in my code:
Qt Code:
  1. value = m_engine.newQObject(m_audio_tracks, QScriptEngine::QtOwnership);
  2. for (i = 0; i < m_audio_tracks->tracks().size(); i++) {
  3. m_audio_tracks->setProperty(QString("%1").arg(i).toLocal8Bit().data(), qVariantFromValue(m_audio_tracks->tracks().at(i)));
  4. value.setProperty(QString("%1").arg(i), m_engine.newQObject(m_audio_tracks->tracks().at(i), QScriptEngine::QtOwnership));
  5. }
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to make it possible to access my object like array from JavaScript.