Ok sweet I see now. They used JavaScriptCore until 2011 or so, switched to V8 until 2013, and have been using their own implementation, q4, since then. The sour

Ok sweet I see now. They used JavaScriptCore until 2011 or so, switched to V8 until 2013, and have been using their own implementation, q4, since then. The source code seems to be here: https://github.com/qt/qtdeclarative/tree/dev/src/qml/jsruntime https://github.com/qt/qtdeclarative/tree/dev/src/qml/jsrunti.... Thanks! Will add and be live shortly.