Get the direction of the text selection

The following function returns forward if user selected text from the left to right. It returns backward in the other case.

const getDirection = function () {
    const selection = window.getSelection();
    const range = document.createRange();
    range.setStart(selection.anchorNode, selection.anchorOffset);
    range.setEnd(selection.focusNode, selection.focusOffset);

    return range.collapsed ? 'backward' : 'forward';
};

Source

https://htmldom.dev/get-the-direction-of-the-text-selection/