How to catch the end of the scroll?

Question

Angular

Good day to all.
There is an Angular application in which one of the modules is written in React (ngReact).
Actually a question on React
Is the Block in which elements are thrown by the list. There is a vertical scroll.
On this block itself there is an onScroll event - how can I calculate that the user has scribbled completely (up as much as possible) \ down as much as possible.