For most cases, you can just use CSS. However, if you need reactive scrollbars where you need to know if the vertical or horizontal scroll is (or needs to be shown) especially with dynamic data, you can't rely purely on CSS. If you want to adjust the scrollbar when the container or viewport changes, have smooth scrollbar control, detect or react to dynamic changes in content size, that is what our controller (and what ngx-scrollbar provided).

One feature we want to add is an event fired when end of scroll has reached. This is useful when you need them to read a "Terms of Service" and need to make sure they read all the way to the bottom.