Use jsdom and jQuery (server-side).

With jQuery you can delete all scripts, styles, templates and the like and then you can extract the text.

Example

(This is not tested with jsdom and node, only in Chrome)

jQuery('script').remove()
jQuery('noscript').remove()
jQuery('body').text().replace(/\s{2,9999}/g, ' ')

The following will wrap all parts that are separated by more than one newline in paragraphs (<p>...</p>) and insert breaks (<br>) where there is just one newline. A text block without any newlines will simply be wrapped in a paragraph.

template = '<p>' + template.replace(/\n{2,}/g, '</p><p>').replace(/\n/g, '<br>') + '</p>';

So for example, it will take this:

Title

First line.
Second line.

Footer

And convert it to this:

<p>Title</p><p>First line.<br>Second line.</p><p>Footer</p>