I am not the maintainer of this code, just a suggestion though:

I would try to keep the "this" inside the showHideScrollIndicators function to be the AlarmList object, as it is for other methods in that object, particularly for the handleEvent method, which is used for event binding. It was initially confusing for me to realize that the `this` in showHideScrollIndicators was actually the this.alarms element.

So, in init, do `this.alarms.addEventListener('scroll', this.showHideScrollIndicators.bind(this));` and then in fillList, just do `this.showHideScrollIndicators()`. And inside showHideScrollIndicators, that should keep the `this` to be AlarmList, and `this.alarms` could be used inside showHideScrollIndicators. I would probably do a `var element = this.alarms` then use `element` or some other var name for the rest of the function.