Review: Greasemonkey Serves Up The Web As You Like It

The glory of open-source software is that it allows anyone with the inclination and the scripting knowledge to get under the hood and hot-rod their computing environment. But most of the time, that advantage is available only to people with the programming skills to make the changes they want. That's where Greasemonkey, a free plug-in for Firefox, comes in -- it simplifies hacking the browser.

Released at the end 2004, Greasemonkey is the latest in a growing arsenal of Firefox customization tools. It changes how Web pages look and act by altering the rendering process. Greasemonkey is to Firefox what aftermarket parts are to cars -- it lets you personalize your browser by making it faster and more powerful or simply by making browsing more aesthetically pleasing. How and why you will use Greasemonkey (and I predict you will, if you don't already) will depend on how you browse now.

Pimp Your Ride
So what does Greasemonkey do? It is simply a means of implementing JavaScript hacks that let users customize their browsing environment, filtering site content or changing page behaviors in ways that make themes and tabbed browsing seem almost quaint by comparison.

Because of Greasemonkey, I will never see another Google AdSense ad again. I can make links to the New York Times site call the printer-friendly (ad-free) version of the page. I'm not a fan of About.com; now I can block those links from Google search returns.

Greasemonkey is more than just TiVO for the Web, however. Want to force Yahoo Mail to use the secure login screen by default? Greasemonkey can help. Want to listen to MP3s in your browser rather than launching RealAudio or Windows Media Player when you click on a URL ending in .mp3? Greasemonkey can help. Want to get rid of an annoying bug in a site you use frequently? Yes, Greasemonkey can help.

The list of scripts is nearly 200 deep and growing every day. Some scripts have universal appeal, like Linkify, which turns text links into clickable URLs. Others are highly individualized, like one that filters out writer Xeni Jardin's posts to the digerati blog Boing Boing. Some are site-specific (Google and Yahoo are favorite targets), while others can be used across the Web.

For those interested in the technical aspects, Greasemonkey loads the script into the Document Object Model (DOM) after the DOM is fully loaded, but before onload occurs. In other words, the script slips in between your browser's capturing of the page code and its display on your screen. According to the World Wide Web Consortium (W3C), the DOM is "is a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure and style of documents." Greasemonkey is basically a GUI into this feature.

Getting Greasy
Installing the Greasemonkey .xpi (Firefox's proprietary extension filetype) is just like adding any other extension or theme to Firefox -- a couple clicks and it's done.

Adding (and removing) the scripts that are Greasemonkey's purview is just as easy. You don't need to restart your browser to implement scripts, so testing them is quick and painless. Once installed, Greasemonkey adds two menu items to Firefox's Tools menu, titled 'Install User Scripts' and 'Manage User Scripts':

There are two ways to install scripts:

To remove a script, simply select Tools > Manage User Scripts and follow the prompts. You can also turn a script on and off by clicking a check box or exclude certain Web pages from being affected by the script.

Itching to create your own hack? Writing a script is relatively easy (assuming you are comfortable with JavaScript), and the Greasemonkey page has a basic tutorial, although it's clearly not intended for the absolute novice. The beauty of Greasemonkey, however, is that since it's open source you can simply copy, paste, and tweak other people's scripts. Filtering the ads from your favorite site is as easy as replacing the URL in an existing script and loading your new script into Firefox.

The Upshot
Not only is Firefox proving to be a powerful means of evangelizing open-source software, but it is leading the charge to draw users up the computing learning curve. Greasemonkey secures Firefox's rightful place in the latest round of the browser wars, and it does so by tapping into those things that make open source so exciting. Greasemonkey harnesses the power of geekdom by providing the casual user with insight into why hackers do what they do.

Politics aside, Greasemonkey is a powerful and exceptionally pleasing tool. It radically enhances your browsing by turning Firefox's already excellent personalization features up another notch.

More Information
• Firefox Central
• Install Firefox
• Install Greasemonkey
• Tutorial: Using Greasemonkey
• Tutorial: Writing User Scripts
• Greasemonkey Script Repository
• Greasemonkey Blog

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