What are the best options for performing Web Scraping of a not currently open tab from within a Google Chrome Extension with JavaScript and whatever more te
I'm not sure it's entirely possible with just JavaScript, but if you can set up a dedicated PHP script for your extension that uses cURL to fetch the HTML for a page, the PHP script could scrape the page for you and your extension could read it in through an AJAX request.
The actual page being scraped wouldn't know it's an AJAX request, however, because it is being accessed through cURL.