Yahoo has stopped work on its Yahoo! User Interface (YUI) project because of the rise of technologies such as Node.js.
“YUI is an important part of Yahoo’s history: millions of lines of code relying on YUI have been written and are still in use at Yahoo today.”
He adds that browser vendors are now committed to making continuous improvements to their web browsers while aligning more closely with standards, concluding that
“with so called ‘evergreen web browsers’, which are making it easier for users to run the latest stable version of a web browser, we can expect a significant reduction in the amount of variance across user agents.”
“new YUI releases will likely be few and far between, and will only contain targeted fixes that are absolutely critical to Yahoo properties.”
YUI is currently at version 3.17.2 and is still available for use.