There's TONS of special cases that can cause this to fail, but I'll present a simple way that will work for you on a decent amount of webpages(but not all).
- save the webpages html source into a local html file.
- edit the html source, adding a
<base href="http://www.amazon.com/"> tag into the <head> element.
- make any other modifcations to the page you want, such as adding new
<script> tags to support your new functionality. Make sure your modifications use absolute urls.
If they navigate away from the page, your enhancements will obviously not carry onto the next page. ALso, you will have more success if you upload the file onto a web server. While a user can view the page by double clicking on the html file if they were to save it locally, differences in javascript security permissions will likely make some webpages not function correctly.
The reason you need to add the <base> tag is because the browser resolves relative urls by looking at the url in its address bar. So, if the amazon page had an image like this
<img src="logo.png">
and you saved the html and put it on you webserver at www.example.com, the browser would look for the image at www.example.com/logo.png, which clearly doesn't exist. The base tag tells it what base url to use.
If you need more automation, having them install a browser addon would be a good way to do this if your users are somewhat technical. Greasemonkey is a popular addon, and you can tell it to inject stuff into certain webpages. The benefit of an addon is that it can inject the new functionality into any page on the web, without you having to individually save and modify them. Also, it has the potential to work on all web pages, leaving their functionality perfectly in tact, opposed to the other suggestion. This is far more complicated though.
