Retain Text Formatting From Web Page

Apologies for the almost duplicate post but thought this was much
clearer description of the issue than what I originally posted.

I'm trying to do simple integration with a third-party
web application. The app has an 'Action' button on all pages that
can be associate with a JS function. Our application is very
proficient at parsing text provided it is in some reasonably standard structure.

Is what we are trying to do is have a JS function that can be called
from any page in their system that will provide a reasonable representation
of the text on the screen. I need something close to document.body.innerText; the problem with this function is that it strips spacing from tables so we can't get consistent layout.

The consistent layout I am looking for would be the same as if you did
the following on any page:

1) Select all
2) Copy
3) Paste to notepad

Is there a function or process that will retrieve all text and retain
formatting?