Modernizr tests which native CSS3 and HTML5 features are available in the current UA and makes the results available to you in two ways: as properties on a global Modernizr object, and as classes on the <html> element. This information allows you to progressively enhance your pages with a granular level of control over the experience.
Modernizr has an optional (not included) conditional resource loader called Modernizr.load(), based on Yepnope.js. You can get a build that includes Modernizr.load(), as well as choosing which feature tests to include on the Download page.
Run the test suite
MIT license