Grease Monkey is an extension for Mozilla Firefox that allows users to install JavaScript scripts to modify web pages. These user scripts are written by hand and can fix bugs, combine data from multiple pages, or alter formatting and content. However, Grease Monkey scripts may disrupt some websites' revenue or traffic and cause troubleshooting issues if they conflict with the original page code. The scripts also only work on HTML pages and not other technologies like Flash.

1. Grease Monkey Interactive Media Device By Jessica Brown

2. What is it? Grease monkey is an extension of Mozilla Firefox that allows users to install scripts when they are needed to most HTML Web pages. Examples: Fixing or rendering bugs Combining data from multiple Web pages

3. Details Grease monkey user scripts are written by hand using a JavaScript code which manipulates contents of Web page using the Document Object Model Interface. Userscript.org maintains a database of Grease monkey scripts, and for each one it lists the URLs of web pages to which the scripts pertain.

4. More Details Writing a Grease monkey script is similar to writing JavaScript for a web page, with some additional restrictions imposed by the security provisions of Mozilla's XPCNativeWrappers. In addition to JavaScript code, Grease monkey scripts contain limited optional metadata, which specifies the name of the script, a description, a namespace URL used to differentiate identically named scripts, and URL patterns for which the script is intended to be invoked or not.

5. Typical Grease Monkey Scripts Auto fill forms. Alter the formatting of text, borders, graphics, etc. Remove specific content, such as advertising, pop-ups, even whole sections of a page. Alter content and layout beyond what the page author considered.

6. More Scripts Add links, buttons, or any other type of HTML element anywhere on the page. Enhance the content of pages by correlating information from related pages on the same site, or other sites. Add extended JavaScript behavior to pages.

7. Problems Possible disruption to revenue of some Websites. Increases in the Web traffic that arise from some scripts. The proliferation of scripts acting on many pages and the difficulty of distinguishing whether problems in a page are caused by actual Web-programming bugs or by local Grease monkey scripts, may make troubleshooting defects more difficult.

8. More Problems Script errors resulting from lack of coordination between Grease monkey developers and the original Website developers. Grease monkey only works on HTML-based pages, and does not work on Java, Flash, Flex, and Silver light content within Web pages. Rich Internet Applications are more difficult for a Grease monkey script developer to control than static Web pages. The original site developers can release a new version of the site that causes the Grease monkey script designed for that site to stop working. There is no official way for user scripts to update themselves; some developers added such functionality to their user scripts but most of them remain static and eventually break.