Simon Willison: Greasemonkey as a lightweight intermediary

The latest release of the swiss army knife of Firefox extensions adds support for cross-domain XMLHttpRequest calls from greasemonkey scripts. What that means is that you can create a user script (a short JavaScript that will be executed whenever your browser loads specific pages) that can then pull extra data in from another server.

Although I still use Safari as my main browser, Greasemonkey really gets me thinking about moving over to Firefox full time. Although I’m still getting my head around everything that Greasemonkey can do, I’m really fascinated by the idea that a web site (and now, if I understand this right, a web application?) can be munged to your needs and preferences so easily. I’ve sampled from the page of available scripts, and I have to say it’s a pretty mind-blowing hack. (Thank you for "fixing" All Music Guide!)

The implications of things like Greasemonkey and PithHelmet catching on seem far-reaching. Think about the benefits of taking web standards to the next level and making sites that can anticipate and acknowledge your visitor’s preferences from their first visit (via standard DIV names or calls to your public “preferences??? file). I wouldn’t begin to know how to make this stuff, but I can definitely see myself becoming a grateful consumer.