Chickenfoot was developed by MIT's User Interface Design Group. It's similar to the Greasemonkey scripting extension for Firefox, but its scripts tend to be simpler and easier for nonprogrammers to customize.
After you download the scripting engine, click View > Sidebar > Chickenfoot (or press F8) to open the Chickenfoot Script Editor. Enter the script in the top pane of the sidebar, and click the Run icon to activate the script for the current page. You can also run scripts by copying and pasting them into the editor, or by clicking the sidebar's Open icon and navigating to the .js file. By placing the scripts in the Triggers window, they will run as soon as the target page opens in Firefox.
A silly example of a Chickenfoot script is one that changes the image on the Google home page. First you copy the script from the Chickenfoot site, and then you paste it into the Chickenfoot script editor, swap out the image-source URL for the one of your choosing, and click the Run icon. Gone is the universally recognizable "Google" icon, and in its place is whatever image you chose. Not especially practical perhaps, but a neat little trick nonetheless.
Another Chickenfoot script places an icon at the end of URLs that lead to a PDF download or anywhere other than a Web page. But the real power of Chickenfoot scripts is in customizing those in the various Chickenfoot libraries.
Keep in mind that malicious scripts can wreak havoc on your system, so be judicious in your use of scripts from unfamiliar sources. Likewise, Chickenfoot may be susceptible to cross-site scripting (XSS), so the developers recommend that you create a separate Firefox profile for Chickenfoot, and use the scripts only on sites you trust.
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