Detect direction of user selection with javascript

Question

I am emulating text editor in my project with custom caret, but native selection. Is there any way how to detect in which direction did user select the text? Lets say, that

Answer 1

I was trying to find a solution that works for me for a couple of days. Here is what I came up with, this will work with single range selection:

var selection = window.getSelection();
var range = selection.getRangeAt(0);
var isSelectionDown = selection.focusNode === range.endContainer;
var isSelectionUp = selection.focusNode === range.startContainer;

The focus node of selection is always where the user releases the mouse, but the range end and start containers change depending on direction.