HOWTO: Make Yahoo! Web Service REST Calls with JavaScript and XMLHttpRequest

Kind of bookmark for myself. Could be useful for you too.

Yahoo! Developer Network - JavaScript Developer Center- HOWTO

AJAX web applications are all the rage these days, and one important aspect of AJAX (the "A" and, depending who you ask, the "X") is a mechanism of making asynchronous connections from the back end of a web application with an object called XMLHttpRequest (XMLHTTP for Internet Explorer). This request is used to retrieve XML or other data from web services such as those provided by us here at Yahoo!. In this HOWTO you'll learn how to make web service requests to Yahoo! Web Services with JavaScript and the XMLHttpRequest object.