Calculating text selection offsets in nest elements in Javascript

Question

The Problem

I am trying to figure out the offset of a selection from a particular node with javascript.

Say I have the following HTML

Answer 1

Just check if your selected element is a paragraph, and if not use something like Prototype's Element.up() method to select the first paragraph parent.

For example:

if(selected_element.nodeName != 'P') {
  parent_paragraph = $(selected_element).up('p');
}

Then just find the difference between the parent_paragraph's text offset and your selected_element's text offset.