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User JavaScript allows you to specify local JavaScript files for Opera to include on every page that you visit.
User JavaScript can be used for many purposes, including:
- Fixing broken scripts on Web pages
- Enhancing Web pages by changing or adding your own content to the page
- Controlling what scripts are allowed to run on a page, and what they are allowed to do
- Simplifying bookmarklets by adding functions they depend on to the User JavaScript
See http://www.opera.com/docs/userjs/ (http://www.opera.com/docs/userjs/) for more details and how to use the scripts.