Website: https://stefansundin.github.io/privatkopiera/

Chrome Web Store: https://chromewebstore.google.com/detail/privatkopiera/jhjhnecocacdbhlkjgpdacoibidhmgdf

Firefox Addons: https://addons.mozilla.org/addon/privatkopiera/

Icon: https://commons.wikimedia.org/wiki/File:VHS_diagonal.svg

Development

The extension directory contains the source code, which you can load directly in Chrome.

The firefox directory contains modifications necessary for the extension to run in Firefox (currently only the manifest file is different). You must run ./make-xpi.sh to copy over the other files, after which you can load the extension in about:debugging.

Bootstrap

To build the custom Bootstrap theme you need Node.js installed and then you can run:

cd bootstrap
npm install
npm run build

If you don't have Node.js or you don't want it, then you can get the default Bootstrap theme by running:

curl -f -o extension/css/bootstrap.min.css https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css

Or just download the file and put it there manually.

Formatting

The JavaScript code is formatted with prettier. The HTML is formatted with the built-in VS Code formatter.

Why are there more executeScript calls than seems necessary?

The extension performs all of its network requests through the host page, using chrome.scripting.executeScript(), for a number of reasons:

1. Any POST request made in the extension will cause Chrome to add an Origin: chrome-extension://jhjhnecocacdbhlkjgpdacoibidhmgdf header. This header is easy to detect and block by websites (see #185). By making the network request from the host page instead, the Origin header will look normal from the website's point of view. There's a Chrome bug about this.
2. The extension can avoid asking for host permissions when the user uses Privatkopiera on a website for the first time. This makes for a better experience since granting new permissions is not foolproof and at least one user reported that they didn't understand how to proceed (see #184).
3. Some websites have permissive CORS permissions initially, but then later make it more restrictive. This makes for an impossible situation since the only workaround would be to ask for host permissions prematurely, even though they may not be required at the time.

executeScript error handling

Firefox has better error handling in its chrome.scripting.executeScript() implementation and populates an error key in the InjectionResult if an error was raised in the script. An issue has been filed to hopefully get the same support in Chrome.

Due to this, where appropriate, return values from executeScript are an object with result or error keys depending on what happened. The complicated scripts are also wrapped in a try-catch clause. This looks funky but will have to do until the situation in Chrome improves.