GNU LibreJS 6.0.4: How to Use

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## 4 How to Use

### 4.1 LibreJS in action

After installing the add-on, you will see the LibreJS widget in the add-on bar at the bottom of the browser window. After loading a page, left-click on the widget to view the deactivated JavaScript code from the page (both on page and external) and, if applicable, the scripts that were accepted.

### 4.2 Complaint Feature

It is very important to complain when a site has nonfree JavaScript code, especially if it won’t work without that code. LibreJS makes it easy to complain by heuristically finding where to send the complaint.

When nonfree/nontrivial code is detected in a page, LibreJS attempts to find a relevant contact link or email for the website you are visiting. In order to do so, it will attempt to visit a few links from the current page (for instance, a link labeled “contact” on the same domain as the current page, ...)

LibreJS can currently detect and list contact pages with webforms, email addresses more likely to be owned by the maintainer of the site, Twitter and identi.ca links, phone numbers.

After LibreJS detects one or more of the above, a small tab will appear on the right of your screen with the LibreJS torch logo. When hovering over the tab, a large panel will slide in with the contact information. Ideally, at the top you will find the email address of the maintainer, labeled as the “Email you should use”.

When you complain to the website for their nonfree nontrivial JavaScript, provide them with the link to the JavaScript Trap essay so that they can get more information on what the issue is and how they can solve it on their own site.

### 4.3 Options

- LibreJS lets you whitelist domain names and subdomains to bypass the regular JavaScript check. This might be useful, for example, if you are running your own code in a local web server. In order to add a whitelisted domain or url, go to Tools >> Add-ons, or press `Control + Shift + A`. Inside the add-on window, click on “Extensions”, and in the list, where you see LibreJS, click on the “Preferences” button. You will see an input field labeled “Whitelist domain”. In the field, enter comma-separated domain names. Do not enter the protocol. For instance to whitelist all the pages of http://www.gnu.org and https://gnu.org, enter “gnu.org”. To allow all subdomains from gnu.org, enter: "*.gnu.org". This will match such sites as http://savannah.gnu.org and http://audio-video.gnu.org.

Next: JavaScript Detection, Previous: Installation, Up: Top [Contents]