How to write your scrollbar via mousewheel?

Question

JavaScript

Good evening. There is a block with a fixed height and width and overflow:hidden on the side is an additional block that plays the role of a scrollbar, relative to the height of the parent block 40% is acceptable. Also a block with info and a height of 10 thousand pc. It is possible without plugins, I don’t think there will be a lot of code. I want to see how it works. I've sketched a frame here. codepen.io/Mackaybravo/pen/KdqRJJ

Answer 1

If you decide to use the plugin, you can try nicescroll, in addition, the scrolling will be smooth if necessary, plus you do not need to bother with scrolling for tablets and phones.
Good luck!