Comment 12 for bug 1733666

Yes, the current way of getting "this" for functions passed to engine.makeConnection is basically the same as arrow functions. However, I don't think it's a great idea to bring in external dependencies to hack around QJSEngine's limitations. I think that effort would be better spent contributing the desired functionality upstream to Qt. I recognize that is likely harder, but I think it would be more sustainable. I also don't think it's a good idea to recommend developers to rely on external JavaScript tooling to write mappings. We can mention that it's a possibility, but I am afraid that setting that up would be such a pain that it would deter people from contributing mappings.

IIRC the ancient QtScript JS interpeter does not support Function.prototype.bind, but I think QJSEngine does. Requiring a call to Function.prototype.bind for every function passed to engine.makeConnection would be annoying, but in general I don't think controller mapping developers should be using engine.makeConnection directly. I think Component.prototype.connect should abstract those details away unless the mapping needs something fancy for a Component with a custom "connect" function implemented.

I am quite confused why Qt hasn't implemented full ES6 support yet considering it uses JavaScript so heavily now. There is an issue on Qt's tracker for this:
https://bugreports.qt.io/browse/QTBUG-47735